PGP Virtual Disks & PGP SDA Cracked!

[nbk2000]

Someone has figured out how to (in certain circumstances) allow an attacker to defeat the security of PGP encrypted volumes and self-extracting archives.

http://www.safehack.com/Advisory/pgp/PGPcrack.html#Two_Ways_to_bypass_PGP_SDA_Authentic ation

Discuss.

[Chris The Great]

Ok, so I read that (and it brought back some fond memories of using a HEX editor to bypass passwords on those annoying admin programs in highschool) and from what I understand, it only works if they have a copy with the original password that they already know.

However, it looks like they are finding a way to work around the password, and may have hit upon something that will eventually lead them to their goal.

Very worrying... I'll definately play around with this though. I'll probably have some better discussion then.

[Jacks Complete]

Currently, it's a big enough hole to worry about. I'd hold off changing systems just yet, though.

The issue isn't with the actual encryption, it is with the authentication of the user. A user who can unencrypt can be revoked normally, but this hack means that they can get back in. This hole only exists if such a user exists. If it doesn't, then there is no risk (currently) as this isn't an attack on the encryption engine itself.

[ravn]

From what I understand, for this to be effective you must,
1. Give your encrypted disk and the master passphrase to a second person.
2. Decide that you no longer want them to access the contents. (change the master passphrase)
3. The second person obtains a new copy of your disk.

This entire scenario can be avoided by reading the manual. From the manual:

Be aware that copies of your PGP Virtual Disk volume use the same underlying encryption key as the original. If you exchange a copy of your volume with another and both change your master passwords, both of you are still using the same key to encrypt the data. While it is not a trivial operation to recover the key, it is not impossible. You can change the underlying key by re-encrypting the volume.

The "attack" only happens when you have added new content to the disk that you do not want anyone else to access. So re-encrypt the volume when you change your passphrase. This whole issue is more of an attack on a persons inability or unwillingness to follow simple security procedures.

This could also be avoided by having the software (pgp) re-encrypt the volume everytime you change the passphrase; however, doing this would negate the ability for people to share an encrypted volume.

my 2 cents.

++++++++

NO self-signing of posts. NBK

[nbk2000]

Everyone keeps focusing on the virtual disk, but ignoring the self-extracting archive crack.

By modifying the SDA file, you can extract the contents without passphrase authentication. THAT is an issue!

Yes, the virtual disk would likely to contain more incriminating information, but the SDA is more likely to contain such things as backup's of your keys, lists of passphrases, or things you'd be sharing with someone else through a pre-arranged passphrase, as it doesn't require keeping around a 'terrorist' application like PGP.

[akinrog]

Yes, the virtual disk would likely to contain more incriminating information, but the SDA is more likely to contain such things as backup's of your keys, lists of passphrases, or things you'd be sharing with someone else through a pre-arranged passphrase, as it doesn't require keeping around a 'terrorist' application like PGP.

Since I'm a paranoid guy, I have been, from the very beginning of my PGP disk use, suspicious of the PGP Enterprise edition which is widely circulated in P2P networks.

After managing to get the FreeOTFE going, I copied pgp volumes from all my DVDs and mounted volumes, copied the content to FreeOTFE volumes and destroyed DVDs together with backups and burned the FreeOTFE volumes on DVDs now.

Maybe I'm exagerating but assume that government applied pressure to authors of the PGP to leave a security hole when certain authorization code (possibly the one supplied with certain copy of Enterprise edition that everyone can get P2P networks) is used. Not impossible IMHO. Regards.

[nbk2000]

I don't use higher the version 7, because the source code isn't publicly available on the newer versions of PGP (AFAIK), thus suspect.

I'm thinking about using OTFE, but PGP 7 is so functional I'm loath to switch. I might start using it for portable USB drives, though.

[akinrog]

I don't use higher the version 7, because the source code isn't publicly available on the newer versions of PGP (AFAIK), thus suspect.

At the beginning, I tried using the last public open source version of PGP (IRRC 6.X.X.X version). However, that version creates a lot of problems on a WinME machine and most importantly on XP machines, despite I used the compatibility mode. :mad:

For example the last open source version mounts volumes but refuses to assign a letter to the volumes. :mad:

So I switched to the widely available version (8.x.x.x) and used it for quite a long time. However all disk volumes are gone now. :D

[Meawoppl]

Guess it is back to the good old "Use once pad" ;p

Switch to linux and get a 4096 bit encrypted partition, and keep your key in a usb drive up your ass.

Nothing beats that security right?