Archive for the ‘General’ category

How can you make your system and documents secure? Today, 256-bit AES encryption is offered by everyone and their dog. However, AES encryption does not mean much (or anything at all) when it comes to the real security of your data. Implementing encryption at the right time and in the right spot is no less important than choosing strong encryption credentials and managing the encryption keys.

While the previous part may sound a bit complicated, it all comes down to much simpler things than choosing the strongest encryption algorithm or selecting the length of the encryption key. If you are a Windows user, it all comes down to choosing the optimal data protection strategy for your particular usage scenario; protecting your storage media and the data you keep on them.

Defining your goals

Before you start considering encrypting your hard drives and files, make sure to define your objectives. What information would you like to protect? What threats do you consider important, less important and quite improbable?

Full-disk encryption part I: protecting your boot device

A reliable system protection is impossible without protecting your boot device. An unencrypted boot device (disk C: on most systems) allows for way too many vectors of attack ranging from hibernation and page file analysis to instant extraction of stored passwords from your Web browser vault. In other words, securing your boot device with BitLocker is an absolutely mandatory preliminary step and the most important security layer.

  • Availability: Windows 10 Professional and higher with TPM2.0, Intel PTT or Group Policy edit; all Windows editions for device encryption in thin and light devices meeting minimum requirements.
    • Note: although Windows 10 Home cannot natively create new BitLocker volumes, it can unlock BitLocker encrypted drives with full read-write access
  • Physical access, hard drive only: strong protection
  • Physical access, entire computer: it’s complicated
  • Other users on the same computer: not applicable
  • Malware/ransomware: not applicable
  • Online attacks: not applicable
  • Usage cases: protect data against theft of computer or hard drive; protect data if hard drives are sold or RMA’d; protect data against physical extraction.

If your computer meets the requirements (namely, the presence of a hardware TPM2.0 module or software-based Intel Platform Trust Technology), enabling BitLocker on your computer can be as easy as opening the Control Panel and launching the BitLocker Drive Encryption applet. Note that not all editions of Windows 10 can use BitLocker protection.

We have a comprehensive article on BitLocker protection in our blog, which is highly recommended. Introduction to BitLocker: Protecting Your System Disk

What caveats are there when it comes to securing data against physical extraction? The thing is, while BitLocker is nearly a 100% effective solution for protecting the bare drive, it might not be as secure if the intruder has access to the entire computer with the hard drive installed. Even if your computer is equipped with a TPM2.0/Intel PTT module, Windows will still unlock the encrypted hard drive if Secure Boot conditions are met. This in turn opens numerous vectors of attack that may allow the intruder to intercept the on-the-fly BitLocker encryption key and decrypt the hard drive. These vectors of attack include:

  1. Making a RAM image of a running computer with BitLocker volume(s) mounted. This can be done via a Thunderbolt attack (Windows, by default, does not disable Thunderbolt DMA access when locked) or a cold boot attack.
  2. Breaking or extracting your Windows logon password (e.g. extracting from your Google account, your smartphone, or from another computer you have logged in and synced your data to).
  3. Obtaining your BitLocker Recovery Key from your Microsoft Account or Active Directory.

Advanced users and system administrators can read the following guide to secure their BitLocker volumes: BitLocker recovery guide

Full-disk encryption part II: protecting external storage devices

BitLocker is good not only for protecting your boot device, but for encrypting data on other volumes, built-in and removable. BitLocker protects external storage devices with BitLocker To Go, an encryption algorithm based on a password. In addition to passwords, external drives encrypted with BitLocker To Go have an option to unlock with a smart card on another computer by using BitLocker Drive Encryption in Control Panel. Finally, users can opt to make their encrypted external devices automatically unlock when connected to their (trusted) computer.

  • Availability:
    • Encrypt external devices: Windows 10 Professional and Enterprise
    • Access BitLocker encrypted devices: although Windows 10 Home cannot natively encrypt drives with BitLocker, it can access BitLocker encrypted drives with full read-write access
  • Physical access, device only: protection as strong as your password
  • Physical access, entire computer: it’s complicated (see previous chapter)
    • Note: if you enabled the option “Unlock automatically on this PC”, then effectively no protection
  • Other users on the same computer: strong protection if offline/not mounted
  • Malware/ransomware: strong protection if offline/not mounted
  • Online attacks: strong protection if offline/not mounted
  • Usage cases: protect data stored on external storage devices such as external drive enclosures, USB flash drives etc.

Unlike system drive encryption, BitLocker To Go does not support multifactor authentication. This means you cannot use TPM protection as an additional form of authentication. You can, however, make BitLocker To Go devices unlock automatically when they are inserted in your (trusted) computer, which carries obvious security implications.

Full-disk encryption part III: using third-party crypto containers

I put it here just for the sake of completeness. If you are considering using a crypto-container such as VeraCrypt or PGP, you probably know what it is good for and how to use it. I’ll just add several things that aren’t immediately obvious when you set up encryption. In fact, the two things are so non-obvious that many coach experts have it backwards. (The right way: Choosing the right hashing algorithm – it’s all about slowness).

  • Availability: VeraCrypt is available on most relevant platforms
  • Physical access, hard drive only: very strong protection unless misconfigured
    • Misconfiguration examples: volume stays mounted when computer sleeps or hibernates; volume stays mounted when computer is locked (matter of security vs. convenience); volume unlocked with security key (e.g. USB flash drive) and no password (if USB flash drive is discovered)
  • Physical access, entire computer:
    • volume not mounted at time of analysis: very strong protection
    • volume mounted: very little protection
  • Other users on the same computer
    • volume not mounted at time of analysis: very strong protection
    • volume mounted: very little protection
  • Malware/ransomware: same as above
  • Online attacks: same as above
  • Usage cases: protect data against theft of computer or hard drive; protect data if hard drives are sold or RMA’d; protect data against physical extraction.

The choice of encryption algorithm (spoiler: use AES)

Crypto containers such as VeraCrypt offer the choice of several (actually, multiple) encryption algorithms that range from the industry-standard AES to some quite exotic algorithms such as Serpent or Kuznyechik. For the paranoiacs among us, VeraCrypt offers stacked encryption (e.g. the Serpent(AES) option). The thing is, the choice of an encryption algorithm does not affect the security of your data (unless you pick an algorithm with known or suspected vulnerabilities; finger pointed to Kuznyechik).

The choice of encryption algorithm does not affect the security of your data. A single round AES-256 encryption will be exactly as secure as Serpent(AES) or Serpent(Twofish(AES)). Moreover, the choice of encryption does not even affect the recovery speed (the speed of brute-force attacks on your password)!

Considering that AES is the only hardware-accelerated encryption algorithm in all reasonably modern processors, choosing any encryption algorithm other than AES-256 will unnecessarily slow down your reads and writes (expect a difference of 2 to 3 orders of magnitude in theoretical RAM-to-RAM encryption speeds) without providing any additional security benefit.

If choosing an encryption algorithm other than AES does not affect security, then what does?

The choice of hashing algorithm

When VeraCrypt encrypts (or decrypts) your data, it is using a binary encryption key to perform symmetric cryptographic operations. This media encryption key (MEK) is stored along with the encrypted data. The Media Encryption Key (MEK) is encrypted with a Key Encryption Key (KEK), which, in turn, is the result of multiple (hundreds of thousands) iterative hash operations performed on the user’s password.

In other words, when you type a password, the crypto container will perform a calculation of a certain hash function, and repeat that a 100,000 times or more (in order to deliberately slow down brute-force attacks).

If you want to make your encrypted volume more secure, you can change one of the two things:

  1. Increase the number of hash iterations
  2. Don’t use defaults
  3. Choose a slower hash function

VeraCrypt allows modifying the number of hash iterations by adjusting the PIM (Personal Iterations Multiplier); here is the how-to. The PIM value controls the number of iterations that is used to derive the encryption key from the password that you type. This value can be specified through the password dialog or in the command line. If you don’t manually specify the PIM value, VeraCrypt will use the default number of iterations, which is bad because (2). For SHA-512 or Whirlpool (the two recommended choices), VeraCrypt defaults to Iterations = 15000 + (PIM x 1000).

Why would you want to change the number of hash iterations? Because an attacker will first try to break your password using the defaults. Most tools used by the attackers to brute-force your password will first run the attack using all-defaults: the default encryption algorithm (AES), hash function (SHA-512) and PIM. Changing the PIM value is an easy way to substantially increase security without making your password more complex. Changing the hashing algorithm from default (SHA-512) to Whirlpool also makes sense in this context.

Which brings us to the choice of a hashing algorithm. VeraCrypt offers the choice of SHA-512 (slow, good choice), Whirlpool (slower, even better choice), SHA-256 (slow, but not as slow as SHA-512, use other hash instead), and Streebog (untested). Choosing the right hashing algorithm – it’s all about slowness has some benchmarks and some good explanations; highly recommended. Selecting Whirlpool makes a lot of sense because a) it is slower than SHA-512 (thus will be significantly slower to attack), and b) it is a non-default selection, which significantly increases the complexity of the attack.

File system encryption: when and how to use EFS

If you read the Wikipedia article about Microsoft Encrypting File System (EFS), you’ll get that EFS has been introduced in NTFS 3.0 in order to provides file system level encryption. The article reads: “The technology enables files to be transparently encrypted to protect confidential data from attackers with physical access to the computer.”

While all of that is interesting, neither statement explains who and, most importantly, why should be using EFS, and what exactly the encrypting file system protects against.

  • Availability: all versions and all editions of Windows 10 (and most older versions of Windows)
  • Physical access, hard drive only: as strong as your Windows account password
  • Physical access, entire computer: same as above
  • Other users on the same computer: effective protection
  • Malware/ransomware: not applicable
  • Online attacks: not applicable
  • Usage cases: protect your documents from other users of your computer; an extra layer of security on BitLocker-protected drives; reasonably strong, very easy and fully transparent document encryption on computers where BitLocker is not supported.

What does EFS protect against, and who should be using it?

The purpose of Encrypting File System is protecting your data from users who share your computer. If you have a PC with several users, and each user has their own Windows login (as opposed to sharing a single Windows account), activating EFS encryption is the easiest way to protect your files from being accessed by those other users.

What is the relation between EFS and BitLocker, and which one should you use?

BitLocker protects your entire system volume. Any user who can log in to your computer will unlock the system volume. If a user has administrative privileges (or can escalate a non-admin account by using an exploit), he or she will also gain access to files and documents stored in other users’ accounts on that computer.

Encrypting File System, on the other hand, only protects selected folders. It won’t, for example, protect your instant messenger databases or encrypt your browsing history. It’s mostly just for documents, pictures and videos you keep in your account. However, EFS will effectively protect those files against other users who can log on to your computer, even if they have administrative privileges.

If an attacker got physical access to the computer, BitLocker is the first line of defence. Relying solely on EFS to secure the PC against attacks with physical access is not the best idea.

How does it all work? It’s actually quite simple. Right-click on a file or folder you’d like to encrypt, select Properties and click the Advanced button in the General tab. In the Advanced Attributes dialog select Encrypt contents to secure data and click OK.

This is it. Windows will now encrypt the selected file or folder with your Windows logon credentials. There are no passwords to type and no encryption keys to save.

There is a certain drawback to using EFS encryption. If you ever forget your Windows password and have to reset it from a separate Administrator account (or your domain administrator resets the password for you), the EFS encryption keys will be lost, and you will be unable to decrypt your data without going through the data recovery process with Elcomsoft Advanced EFS Data Recovery. Note that you must recover your Windows password in order to decrypt the files. However, if you simply change your Windows password by following the normal procedure (typing your old password followed by entering the new one), you will be fine.

Document encryption

Encrypting individual documents is an important part of multi-layer security. Microsoft Office apps can use passwords to encrypt the documents’ content. No one without a password should be able to decrypt the document.

  • Availability: all versions of Microsoft Office
  • Security: depends on the version of Microsoft Office, the file format you’re using to save the files and the strength of your password.
  • Physical access, hard drive only: strong protection (with caveats)
  • Physical access, entire computer: strong protection (with caveats)
  • Other users on the same computer: strong protection (with caveats)
  • Other users on your Local Area Network: strong protection (with caveats)
  • Malware/ransomware: content protection. Malware won’t be able to decrypt your files and read your data. However, malware/ransomware can still encrypt your files, effectively locking you out.
  • Online attacks: content protection. Strong protection against unauthorized data access; no protection against unauthorized deletion
  • Usage cases: protect the content of your documents against anyone who does not know the encryption password.
  • How to: Protect a document with a password

A million dollar question: if you are on a local area network, should you use EFS or document encryption to protect documents against other users on the same LAN? In this case, it’s better to use both. EFS will make it impossible to gain access to encrypted files and folders without knowing your Windows account/domain credentials. Password protection of individual documents will make documents difficult to break even if the attacker knows your logon credentials.

The caveats of document encryption

So what exactly does “strong protection (with caveats)” mean? The thing is, your documents are just as secure as the password you use to protect them. If you re-use a password you already stored in your browser cache or in the keychain, extracting that password and decrypting the documents will be a matter of minutes in many types of attacks.

What if you use a cryptographically strong and truly unique password to encrypt documents? Are these documents secure? The thing is, they will be just as secure as the office app permits them to be. In Microsoft Office encryption evolution: from Office 97 to Office 2019 I discussed the encryption algorithms and protection strength of Microsoft Office apps from the early days to the most current release.

Generally speaking, everything before Office 2000 was insecure (no protection). Office 2000, XP and Office 2003 had very weak encryption that can be usually broken in under a day.

Since Office 2007, Microsoft started taking encryption seriously. Office 2010, 2013, 2016, 2019 brought security to the new level, making encrypted documents very secure.

Okay, so you are using the latest Office and selected a strong password; are we secure now? The thing is, you’ll be just as secure as the document format allows. If you are using the newer DOCX/XLSX format (files with .docx / .xlsx extensions), you’re good. If, however, you are saving your documents in “compatibility” mode, you are sacrificing encryption and make your documents as vulnerable as if they were saved by an Office 2003 app.

Best practices:

  1. Use the latest version of Microsoft Office to save documents. If the latest version is not available, use at least Office 2013 (the newer the better).
  2. Never save documents in “compatibility” mode. Make sure that the files are DOCX/XLSX as opposed to DOC/XLS.
  3. Use a unique, cryptographically strong password to encrypt documents. Remember: if the password is broken once (e.g. pulled from your Google account or recovered from a document you accidentally saved in the “compatible” format), it will be used to break everything else, including documents with strong encryption.
  4. If you email an encrypted document, do use a unique, one-time password for that document, and never send both the document and the password in the same email. In fact, you should never send the password by email since that would allow an attacker who gained access to your email account to decrypt the document. Send the document and the password via separate communication channels (e.g. email / text message, chat or phone call).

Protecting backups and archives

Making regular backups is a common wisdom. Protecting those backups is a wisdom much less common. Once you make a backup, make sure to give it as strong a protection as your boot drive.

  1. Store backups on BitLocker-protected media. Even if your backup tool (e.g. the one built into Windows) does not support encryption, at very least your storage media is protected with full-disk encryption. Note: Windows 10 does support the recovery from BitLocker-protected disks. Just create a bootable install image from Microsoft Web site (use “Create Windows 10 installation media”).
  2. If your backup tool supports encryption, it may be a good idea to encrypt your backups (AND store them on a BitLocker-protected media). Note, however, that a backup tool will probably cache (store) your backup password on your computer to automatically encrypt new and incremental backups. For this reason, make sure to have a truly unique, never reused password for encrypting backups.

Individual folders are frequently backed up using common archive tools such as WinZip, 7Zip or WinRar. All of these tools offer the ability to encrypt archives with a password. While the encryption strength is different among the three formats (ZIP, 7Z and RAR), an up to date version of each tool provides adequate protection if you choose a reasonably complex password (e.g. 8 characters or more, combining small and capital letters with numbers and special characters). To achieve the best level of protection, do keep those archives on BitLocker-protected media.

Note that password recovery tools work significantly faster on ZIP/7Z/RAR compared to attacking BitLocker encryption or Office 2013 (and newer) documents. For this reason, never reuse your password, and make sure that your BitLocker media, your documents and your backups/archives use very different passwords (ideally, not based on the same pattern).

More information:

Cloud security: OneDrive Personal Vault

Microsoft started offering an extra layer of security to all users of its cloud storage service in the form of a Personal Vault. OneDrive Personal Vault helps secure your files both on your computer and in the cloud in the event that someone gains access to your account or your device.

Unlike ransomware protection, Personal Vault is available to all users of Microsoft OneDrive and not just to Office 365 subscribers. Technically speaking, Personal Vault is an area in the OneDrive folder on your computer and in the OneDrive cloud storage that features additional protection. You can only access this protected area after passing a strong authentication. If your Microsoft Account is protected with two-factor authentication, you will have to pass the second step of identity verification in addition to typing your Microsoft Account password.

Once configured, Personal Vault must be manually unlocked every time you need access to secured data. To unlock, you must type in your Microsoft Account password and pass the second authentication step if your account has two-factor authentication. Once you’ve finished accessing the data, Personal Vault will automatically relock after a short period of inactivity. Once locked, any files you were using will also lock and require re-authentication to access.

Setting up Personal Vault only takes a few clicks as outlined in Protect your OneDrive files in Personal Vault.

OneDrive Personal Vault is still new; no independent security analysis has been performed until today. In our view, Personal Vault is worth consideration as an extra security layer for some of the most private but rarely accessed types of data. Examples of such data may include BitLocker escrow keys and binary encryption keys, or the list of passwords some users store in encrypted Excel spreadsheets. I personally keep my two-factor authentication secrets (scanned QR codes to initialize the Authenticator app) in the Vault as well.

  • Physical access: unknown (not yet analyzed)
  • Other users on the same computer: strong protection
  • Malware/ransomware: strong protection (unless Personal Vault is unlocked at the time malware is running)
  • Online attacks: as strong as your Microsoft Account security
  • Usage cases: activate to add an extra layer of security for a handful of personal documents, encryption keys, 2fa secrets etc.

 

Ransomware protection

One of the most important threats not covered by any encryption is the type of malware called ransomware. Ransomware is a type of malware that threatens to either publish the data stolen from the victim or perpetually block access to the victim’s files by encrypting them with a key that is only known to the attacker. The term ‘ransomware’ has emerged from the fact that, on many cases, attackers demand a ransom payment to decrypt data.

Protecting your data against ransomware is a complex topic in itself. However, computer users can choose one or both of the following two defences when it comes to ransomware protection.

Ransomware protection is effective against the following threats.

  • Physical access: no protection
  • Other users on the same computer: no protection
  • Malware/ransomware: effective protection
  • Online attacks: as strong as your cloud account security
  • Usage cases: available automatically to Office 365 subscribers. Available to paid Dropbox users. Automatically protects files stored in OneDrive/Dropbox. Automatic alerts (OneDrive only). Automatic restore (OneDrive only); manual restore (Dropbox).

Use cloud storage with automatic ransomware protection

If you are using Windows 10, most likely you already have a Microsoft Account. The Microsoft Account gives you access to OneDrive, Microsoft’s cloud storage solution. The free tier includes 5 to 15 GB of online storage, while Office 365 subscribers receive the whole terabyte of cloud storage.

Microsoft actively promotes OneDrive Ransomware Protection. OneDrive automatically detects when the files are mass-deleted or mass-edited (such as when ransomware encrypts the entire Documents folder), alerts the user and prompts to restore the known-good snapshot. The File Restore feature is only available to Office 365 subscribers (Home and Personal levels are enough to receive protection).

More information at Ransomware detection and recovering your files.

If you prefer Dropbox to Microsoft OneDrive, Dropbox gets you covered against ransomware attacks, but mostly for higher-level paid tiers. Users of the free Basic tier as well as Plus subscribers can roll back individual encrypted files during the first 30 days after the attack (there will be no warning of mass-deletion of mass-encryption of files coming from the Dropbox app). If you want to roll back the entire Documents folder with Dropbox Rewind, you’ll need to be a paid Plus or Professional tier subscriber.

More information:

Make backup snapshots. Keep backup media offline

Once ransomware is installed on your computer, it will try to encrypt every document that is accessible. The obvious solution is making documents inaccessible by physically disconnecting backup media (such as using 2.5” portable USB drives to back up). In this scenario, you would only connect backup media to your computer when you actually want to make the backup, disconnecting the disk after the backup tool finishes its job. With this approach, even if your computer is attacked by ransomware, your offline backups will not be affected (unless you connected the external drive to the computer at the time the ransomware was installed).

In addition, configure your backup tool to keep snapshots of your data going back as long as permitted by available storage. In our office, an affordable 4TB USB hard drive can keep approximately 30 to 40 full snapshots of the Documents folder; this number becomes significantly larger if you enable incremental backups, with each snapshot saving only

More information:

 

Thecus has been manufacturing NAS devices for more than 15 years. The company develops an in-house Linux-based NAS OS, the ThecusOS. At this time, the most current version of the OS is ThecusOS 7. Thecus advertises secure data encryption in most of its NAS devices. The company’s volume-based encryption tool allows users to fully encrypt their entire RAID volume, defending essential data in instances of theft of the physical device. We found Thecus’ implementation of encryption somewhat unique. In this research, we’ll verify the manufacturer’s claims and check just how secure is Thecus’ implementation of 256-bit AES encryption.

Abstract and Summary

Thecus uses volume-based 256-bit AES encryption with a single, fixed, unchangeable encryption key. The 3968-byte (31744-bit) encryption key file is generated at the time the user creates a new encrypted volume based on the user’s password (4-16 characters, 0-9, a-z, A-Z only). Creating several encrypted volumes with the same password produces different encryption key files.

The encryption key is stored on an external USB drive (the only, forced option) and does not have any additional protection.

The encrypted volume is automatically unlocked once the user inserts the USB drive that contains the correct encryption key.

The original password the user typed when creating an encrypted volume is never used again, anywhere. Users cannot change the encryption password. Users cannot encrypt existing data. Users cannot permanently decrypt encrypted volumes. Any changes to encryption require deleting and re-creating the volume and filling it up with data. The entire encryption scheme lacks any sort of technical documentation.

The entire protection scheme is completely undocumented. For example, it is not clear what the password is used for since the user never has to type it again (ever) to mount or otherwise access encrypted volumes.

Note: SED is supported by ThecusOS but was not tested in our lab.

Test Bench

We analyzed a Thecus N2810 device based on an Intel Celeron Processor N2810. A non-SED WD Red HDD was used to set up the NAS perform the analysis. The NAS was running on the latest available version of ThecusOS 7.

Volume-Based Encryption

ThecusOS supports volume-based encryption. Unlike folder-based encryption that allows protecting (or not protecting) individual shares, volume-based encryption protects the entire RAID volume. The closest analogy to volume-based encryption would be BitLocker in Microsoft Windows or FileVault 2 in Apple macOS. However, the Thecus implementation is significantly more basic compared to Apple’s or Microsoft’s full-disk encryption tools.

Encrypting

Users can only encrypt newly created, empty RAID volumes (regardless of the number of disks; a single-disk RAID volume can be encrypted just as easily as a volume spanning across multiple physical disks).

Encrypting an existing volume is not possible. One must first remove the volume, create a new one and tick the “Encrypt” box. As a result, encrypting volumes with existing data is not supported.

The first step is creating a new volume:

The optional encryption feature requires a password. The password must be 4 to 16 characters long; character groups 0-9, a-z, A-Z are supported (no special characters and no local characters).

Users don’t have to memorize that password as they’ll never have to type it again to access the encrypted data. Instead, ThecusOS will generate a 3968-byte (31744-bit) encryption key, and store that key on an external USB drive that must be connected to the NAS at the time the encrypted volume is created.

Once the user inserts an external USB drive (e.g. a flash drive) into one of the available USB ports, the NAS saves the encryption key on that drive and creates and mounts the encrypted volume.

Mounting encrypted volumes

The encrypted volumes are mounted automatically when the user inserts a USB drive that contains the volume encryption key into any available USB port on the Thecus NAS. There are no additional prompts, and there is no need to open the Web UI.

The following scenarios are supported.

  1. The NAS is powered on or rebooted; no USB drive containing the encryption key is inserted. In this case, the encrypted volume is locked, and the data is not accessible.
    However, the NAS can still complete the boot sequence as the main OS (and some configuration files) are stored on a small NAND storage chip and not on the hard drive(s).
  2. The NAS is powered on or rebooted; the USB drive containing the encryption key is inserted. In this case, the encrypted volume will be mounted by the time the device completes the boot sequence.
  3. The most interesting scenario is when the NAS is powered on or rebooted without a USB drive inserted, and the user inserts the USB drive containing the encryption key at a later point. In this case, the OS will automatically recognize the USB drive, read the encryption key and automatically mount the encrypted volume.

Locking encrypted volumes

As we figured, encrypted volumes are mounted automatically when the user inserts the correct USB drive. What happens after the USB drive is removed? In this case, the NAS keeps the encrypted volume mounted. The volume remains mounted until the NAS is powered off or rebooted, or until the user manually locks the volume through the Web UI.

Decrypting

If you are used to BitLocker, you probably know it is easily possible to remove the password from an encrypted volume. Interestingly, BitLocker will not decrypt any data that has already been encrypted; instead, it’ll just store the unwrapped encryption key in the volume header, allowing the system to pick up the key and access information without a password. Any new information saved on such BitLocker volumes would be saved unencrypted.

With Thecus, the situation is much simpler. Users cannot remove encryption or permanently decrypt encrypted volumes, period. The only way to permanently decrypt the data is removing the encrypted volume, re-creating the volume without encryption and filling it up with data.

Changing the password: impossible

Decades ago, manufacturers came up with a brilliant idea of separating the binary keys that are used to actually encrypt and decrypt the data, and user-provided secrets that are used to access the data. In symmetric cryptography, only one unique binary encryption key may be used to encrypt and decrypt the data; this is called the Media Encryption Key (or Data Encryption Key). However, users can unlock encrypted data by using multiple different types of credentials such as plain-text passwords, credentials stored on secure smart cards or TPM modules, binary keys (files) or combinations of thereof. These credentials (Key Encryption Keys) are used to encrypt (wrap) the Media Encryption Key. Multiple different Key Encryption Keys may be used to wrap the same Media Encryption Key, allowing the user to instantly change their plain-text password, add or remove smart cards and other credentials.

ThecusOS 7 does not use the concept of Key Encryption Keys. The user’s original plain-text password is used to produce a single, fixed Media Encryption Key. Neither the password nor the encryption key can be changed after the volume is encrypted.

Observations

While users are required to enter a password when encrypting the volume, this password will never be used again anywhere in the ThecusOS interface. I was unable to find any references to this password in the Thecus technical documentation or the online knowledge base. The password is not used to decrypt data or to mount encrypted partitions. Users will never have to type that password again. In other words, the password seems completely redundant in this setup. The lack of a proper explanation, let alone comprehensive technical documentation, makes me shake my head.

ThecusOS produces different encryption keys when creating volumes protected with the same password. This is a good hint that the password is salted with some random data. The lack of proper documentation makes this guess as good as any others.

Thecus and SED Encryption

ThecusOS supports SED (Self-Encrypting Drive) encryption, as seen on the screen shot below.

We have not tested the SED implementation due to the lack of a compatible hard drive. Considering the cost and market positioning of the Thecus N2810, the model is likely to be used with consumer-grade NAS hard drives such as the Western Digital Red or Seagate Ironwolf series, both of which lack the SED support.

What Risks Are Covered by Thecus Security Model

The security model employed by the ThecusOS is stripped down to the bare essentials. I have the following remarks about the Thecus security model.

  1. It is not clear why the system prompts for a password if that password cannot be used to unlock volumes and cannot be changed. If the user’s password is only needed as a random seed of a sort, this must be properly disclosed and documented.
  2. The lack of any sort of technical documentation for the data protection scheme is discouraging. This might be passable for the home user and occasional small office use, but unacceptable for anything beyond that.
  3. The encryption key is stored on a separate USB drive. Users can conveniently insert that USB drive at any time to automatically unlock encrypted volumes. As a result, the entire protection scheme is based exclusively on “something you have”. Anyone who has access to the USB drive holding the encryption key will be able to mount encrypted volumes.

As one can see, it all comes down to whether or not the attacker has access to the USB drive containing the encryption keys.

If the USB encryption key is stored separately of the NAS unit, and the NAS is powered off, the encrypted data is protected against the theft of the hard drives and the theft of the whole NAS unit.

If the attacker has access to both the NAS unit and the USB drive containing the encryption key, the protection is nil.

Conclusion: Thecus Encryption vs. Microsoft BitLocker

When it comes to full-disk encryption, Microsoft BitLocker and Apple FileVault 2 are the first things that come to mind, with TrueCrypt and VeraCrypt being the most popular third-party implementations. Secure encryption, comprehensive key management and multiple methods for encrypting and unlocking volumes are supported by all of these crypto-containers.

When it comes to attached storage encryption, you are welcome back to the Stone Age. A typical NAS advertising 256-bit AES encryption lacks any kind of key management; often to the point the user cannot even change their encryption password without deleting the entire volume, re-creating, re-encrypting and re-filling with data. Many NAS manufacturers have no idea about the existence of separate Media Encryption Keys and Key Encryption Keys, let alone their multiple instances. A typical NAS sold to a home or small office user does not allow encrypting existing data or removing the password from encrypted volumes should you no longer need to protect them.

All of these statements are true for the ThecusOS 7. The lack of even the basic key management, the inability to change the encryption password, and the inability to encrypt or decrypt existing volumes makes Thecus NAS encryption one of the least flexible ever. The protection system lack transparency or any sort of technical documentation. How does the system come up with a 3968-byte encryption key based on the user’s 4 to 16-character password? In a case of data loss, is it possible to decrypt the data with the user’s password instead of the encryption key? Does the key contain the user’s password, the hash of a password, or is it mostly random data? None of these questions have answers in the technical documentation.

At the same time, the encryption implementation is simple and straightforward. Based on a file stored on a removable USB drive, the data would be impossible to decrypt without said USB drive (unless a vulnerability is found). This encryption would likely be sufficient to protect most data stored by home and small office users.

For us, this year has been extremely replete with all sorts of developments in desktop, mobile and cloud forensics. We are proud with our achievements and want to share with you. Let’s have a quick look at what we’ve achieved in the year 2019.

Mobile Forensics: iOS File System Imaging

We started this year by updating Elcomsoft iOS Forensic Toolkit, and by a twist of a fate it became our most developed tool in 2019. The developments went through a number of iterations. The release of unc0ver and Electra jailbreaks enabled Elcomsoft iOS Forensic Toolkit to support physical acquisition for iOS 11.4 and 11.4.1 devices, allowing it to produce file system extraction via jailbreak.

In the meanwhile, we updated Elcomsoft Phone Viewer with support for file system images produced by GrayKey, a popular forensic solution for iOS physical extraction. Analysing GrayKey output with Elcomsoft Phone Viewer became faster and more convenient.

Later in February, Elcomsoft iOS Forensic Toolkit received a major update, adding support for physical acquisition of Apple devices running iOS 12. The tool became capable of extracting the content of the file system and decrypting passwords and authentication credentials stored in the iOS keychain. For the first time, iOS Forensic Toolkit made use of a rootless jailbreak with significantly smaller footprint compared to traditional jailbreaks.

Not long ago, Elcomsoft iOS Forensic Toolkit 5.20 was updated with file system extraction support for select Apple devices running all versions of iOS from iOS 12 to iOS 13.3. Making use of the new future-proof bootrom exploit built into the checkra1n jailbreak, EIFT is able to extract the full file system image, decrypt passwords and authentication credentials stored in the iOS keychain. And finally, the sensational version 5.21 raised a storm of headlines talking about iOS Forensic Toolkit as the ‘New Apple iOS 13.3 Security Threat’. Why? We made the tool support the extraction of iOS keychain from locked and disabled devices in the BPU-mode (Before-first-unlock). The extraction is available on Apple devices built with A7 through A11 generation SoC via the checkra1n jailbreak.

Mobile Forensics: Logical Acquisition

Later on, Elcomsoft Phone Viewer was further updated to recover and display Restrictions and Screen Time passwords when analysing iOS local backups. In addition, version 4.60 became capable of decrypting and displaying conversation histories in Signal, one of the world’s most secure messaging apps. Experts became able to decrypt and analyse Signal communication histories when analysing the results of iOS file system acquisition.

Desktop Forensics and Trainings

In 2019 we’ve also updated Advanced PDF Password Recovery with a new Device Manager, and added support for NVIDIA CUDA 10 and OpenCL graphic cards to Advanced Office Password Recovery. Advanced Intuit Password Recovery added support for Quicken and QuickBooks 2018-2019 covering the changes in data formats and encryption of newest Intuit applications. In addition, the tool enabled GPU acceleration on the latest generation of NVIDIA boards via CUDA 10.

We are proud to say that the many changes we implemented in Elcomsoft Distributed Password Recovery are based on the users’ feedback we received by email and in person, during and after the training sessions. We had several trainings this year in the UK, Northern Ireland and Canada. “Fantastic. Time well spent on the training and on software that will be very useful on cases in the future”, commented Computer Forensic Examiner.

Cloud Forensics

We learned how to extract and decrypt Apple Health data from the cloud – something that Apple won’t provide to the law enforcement when serving legal requests. Health data can serve as essential evidence during investigations. The updated Elcomsoft Phone Viewer can show Apple Health data extracted with Elcomsoft Phone Breaker or available in iOS local backups and file system images.

Very soon Elcomsoft Phone Breaker 9.20 expanded the list of supported data categories, adding iOS Screen Time and Voice Memos. Screen Time passwords and some additional information can be extracted from iCloud along with other synchronized data, while Voice Memos can be extracted from local and cloud backups and iCloud synchronized data.

Skype anyone? In December, Elcomsoft Phone Viewer and Elcomsoft Phone Breaker were updated to extract and display Skype conversation histories.

Desktop Forensics: Disk Encryption

Elcomsoft System Recovery received a major update with enhanced full-disk encryption support. The update made it easy to process full-disk encryption by simply booting from a flash drive. The tool automatically detects full-disk encryption, extracting and saving information required to brute-force passwords to encrypted volumes. In addition, the tool became capable of saving the system’s hibernation file to the flash drive for subsequent extraction of decryption keys for accessing encrypted volumes.

Cloud Forensics: iOS 13 & Authentication Tokens

Elcomsoft Phone Breaker 9.15 added the ability to download iCloud backups created with iPhone and iPad devices running iOS 13 and iPadOS. In addition, the tool became able to extract fully-featured iCloud authentication tokens from macOS computers.

Following this, Elcomsoft Phone Breaker 9.30 delivered a new iCloud downloading engine and low-level access to iCloud Drive data. Thanks to the new iCloud engine, the tool became capable of downloading backups produced by devices running all versions of iOS up to iOS 13.2. While advanced iCloud Drive structure analysis allows users to enable deep, low-level analysis of iCloud Drive secure containers.

Cloud Forensics: Google

Elcomsoft Cloud Explorer 2.20 boosted the number of data types available for acquisition, allowing experts to additionally download a bunch of new types of data. This includes data sources in the Visited tree, Web pages opened on Android devices, requests to Google Assistant in Voice search, Google Lens in Search history, Google Play Books and Google Play Movies & TV.

Challenges in Computer and Mobile Forensics: What to Expect in 2020

The past two years introduced a number of challenges forensic experts have never faced before. In 2018, Apple made it more difficult for the police to safely transport a seized iPhone to the lab by locking the USB port with USB restricted mode, making data preservation a challenge. The release of the A12 platform, also in 2018, made it difficult to unlock iOS devices protected with an unknown password, while this year’s release of iOS 13 rendered unlock boxes useless on iPhones based on the two most recent platforms.

On desktop and especially laptop computers, the widespread use of SSD drives made it impossible to access deleted data due to trim and garbage collection mechanisms. The users’ vastly increased reliance on cloud services and mass migration off the forensically transparent SMS platform towards the use of end-to-end encrypted messaging apps made communications more difficult to intercept and analyze.

Sheer amounts of data are greater than ever, making users rely more on external (attached) storage compared to using internal hard drives. Many attached storage devices are using secure encryption, some of them without even prompting the user. Extracting data from such devices becomes a challenge, while analyzing the huge amounts of information now requires significantly more time and effort.

The number of online accounts used by an average consumer grows steadily year over year. While password reuse and the use of cloud services to store and synchronize passwords makes experts’ jobs easier, the spread of secure, encrypted password management services is turning into a new challenge.

Knowing everyday challenges in desktop and mobile forensics, we can now peek into the future. (more…)

Home users and small offices are served by two major manufacturers of network attached storage devices (NAS): QNAP and Synology, with Western Digital being a distant third. All Qnap and Synology network attached storage models are advertised with support for hardware-accelerated AES encryption. Encrypted NAS devices can be a real roadblock on the way of forensic investigations. In this article, we’ll review the common encryption scenarios used in home and small office models of network attached storage devices made by Synology. (more…)

What can and what cannot be done with an iOS device using Touch ID/Face ID authentication as opposed to knowing the passcode? The differences are huge. For the sake of simplicity, we’ll only cover iOS 12 and 13. If you just want a quick summary, scroll down to the end of the article for a table.

BFU and AFU

Let’s get it out of the way: everything that’s listed below applies exclusively to AFU (After First Unlock) devices. You cannot use biometrics to unlock an iOS device that’s been restarted or powered on; such devices are in the state known as BFU (Before First Unlock).

BFU, Before First Unlock: The iOS device was restarted or powered off; you powered it on but cannot unlock it because it’s protected with an unknown passcode.

AFU, After First Unlock: The iOS device was unlocked (with a passcode) at least once after it’s been last rebooted or powered on.

Screen Lock: Unlocking the Device

Touch ID or Face ID can be only used to unlock AFU devices. In order to unlock a BFU device, you’ll have to use the passcode. Even if you manage to bypass the lock screen (via an exploit), you won’t be able to access most device data as it will be encrypted. The decryption key is generated when the user first unlocks the device; the key is based on the passcode.

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If you are working in the area of digital forensics, you might have wondered about one particular thing in the marketing of many forensic solutions. While most manufacturers are claiming that their tools are easy to use and to learn, those very same manufacturers offer training courses with prices often exceeding the cost of the actual tools. Are these trainings necessary at all if the tools are as easy to use as the marketing claims?

We believe so. A “digital” investigation is not something you can “fire and forget” by connecting a phone to a PC, running your favorite tool and pushing the button. Dealing with encrypted media, the most straightforward approach of brute-forcing your way is not always the best.

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Full-disk encryption presents an immediate challenge to forensic experts. When acquiring computers with encrypted system volumes, the investigation cannot go forward without breaking the encryption first. Traditionally, experts would remove the hard drive(s), make disk images and work from there. We are offering a faster and easier way to access information required to break full-disk system encryption by booting from a flash drive and obtaining encryption metadata required to brute-force the original plain-text passwords to encrypted volumes. For non-system volumes, experts can quickly pull the system’s hibernation file to extract on-the-fly encryption keys later on with Elcomsoft Forensic Disk Decryptor.

What’s It All About?

It’s about an alternative forensic workflow for accessing evidence stored on computers protected with full-disk encryption. Once the system partition is encrypted, there is nothing one can do about it but break the encryption. Elcomsoft System Recovery helps launch password recovery attacks sooner compared to the traditional acquisition workflow, and offers a chance of mounting the encrypted volumes in a matter of minutes by extracting the system’s hibernation file that may contain on-the-fly encryption keys protecting the encrypted volumes.

This new workflow is especially handy when analyzing ultrabooks, laptops and 2-in-1 Windows tablet devices such as the Microsoft Surface range featuring non-removable, soldered storage or non-standard media. With just a few clicks (literally), experts can extract all information required to launch the attack on encrypted volumes.

Elcomsoft System Recovery offers unprecedented safety and compatibility. The use of a licensed Windows PE environment ensures full hardware compatibility and boot support for systems protected with Secure Startup. The tool mounts the user’s disks and storage media in strict read-only mode to ensure forensically sound extraction. (more…)

There has been a lot of noise regarding GrayKey news recently. GrayKey is an excellent appliance for iOS data extraction, and yes, it can help access more evidence. As always, the devil is in the detail.

A couple of quotes first, coming from the company who now partners with GrayShift to bundle their mobile forensic software (one of the best on the market, I would say) with GrayKey. They do support GrayKey-extracted data as well, and here is what they say:

“From the first iPhone extraction from GrayKey we were blown away with the amount of data they recovered”

“we’re seeing data we haven’t seen in years”

Actually, this is not exactly the case. Speaking of full file system acquisition, it’s been us who were the first on the market some 3 years ago, see Physical Acquisition for 64-bit Devices, iOS 9 Support.

Since then, we’ve been actively developing and updating iOS Forensic Toolkit, adding support for newer versions of iOS. We published a number of articles in our blog describing the benefits of file system extraction and what you can get: location data, cached mail, app-specific data, CPU and network usage data and much more.

Yes, we use the different approach, that requires jailbreaking (more on that later).

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In our previous article Why SSDs Die a Sudden Death (and How to Deal with It) we talked about SSD endurance and how it’s not the only thing affecting real life reliability. In that article, we assumed that manufacturers’ specifications of certain SSD models remain similar for a given SSD model. In fact, this is not the case. Quite a few manufacturers play tricks with consumers, releasing a certain SSD model with top notch specifications only to downgrade them at some point during the production cycle (but certainly after receiving its share of glowing reviews). While some OEMs do note the change at least in the revision number, the rest will just quote the small print allowing them to “change specifications at any time without prior notice”. We’ve seen well known SSD manufacturers switching from reliable MLC NAND to planar TLC trash within the same model (and zero notice to potential buyers). How can you tell which NAND configuration your particular SSD drive employs and whether or not it lives up to your expectations? Read along to find out.

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