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The Mystery of the Encrypted Gauss Payload

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Re: The Mystery of the Encrypted Gauss Payload

#21

Post by dkokelley »

fryguy wrote: post #4

So does this mean that if you're a high profile target, you should immediately add a random folder to all of your computers in the program files directory?

From a commenter:

"2. Append the pair with the second hard-coded 16-byte salt and bytes 0x15, 0x00 " and assuming point 2 of my message above:

This gives a finger print of all actual used programs. This finger print should be specific in the range of 1 to 10^(-7).

If so specific, it limits the scope to preconfigured systems, which are NOT run under user control.

Might it be, that those targets are embedded systems like ATM, Mobile base stations and again SCADA-systems?

Supposedly an administrator could send an update that inserts random files in program files to foil the system identification method, but given that the attacker has such detailed information about the target systems, this seems like a temporary measure at best.

Edit: It looks like the code is only looking for a specific filename. In that case, the only way to thwart this is to rename that file (and fix any issues that this would cause).

Re: The Mystery of the Encrypted Gauss Payload

#22

Post by pruman »

lifeisstillgood wrote: post #18
sounds wrote: post #15

Earlier quoted context omitted.

The full implications of this code are that the attacker already has another channel to access your machine. It's not much consolation that you now know that you're being targeted by the Program Files entries (they're a major pain to rename). It's likely there are one or more plants inside your operation and they have physical access to the machine, which is considered game over.

oh, this is the modern version of a microdot Release Gauss into the wild, have your agent in Fordu Nuclear plant be sure he has Gauss on his machine, and then just get him to name the jpgs or text files he wants sent back to the CIA as 'special.jpg' - Gauss nabs them, sends it back through the network of gauss infected machines, and hey presto - deniable, encrypted, distributed Dead Drops. Wow. Clever. Thank you

Clever. The font makes it possible for the agent to verify he is on a Gauss machine by visiting seemingly innocuous websites which have code to detect whether the font exists, and then inform him by outputting special text only he knows about. He could receive messages that way too. Once he knows it's a Gauss machine, he can drop his specially named files and they are delivered.

Re: The Mystery of the Encrypted Gauss Payload

#23

Post by dkokelley »

mjs wrote: post #19

So whilst the malware will infect machines more or less indiscriminately, the payload itself can only be successfully decrypted (and therefore activated and executed), on machines that have a specific set of programs installed?

I think it's actually just one specific program, who's name starts with a special character or high UNICODE character.

Re: The Mystery of the Encrypted Gauss Payload

#24

Post by kuriraisu »

pruman wrote: post #22
lifeisstillgood wrote: post #18

Earlier quoted context omitted.

oh, this is the modern version of a microdot Release Gauss into the wild, have your agent in Fordu Nuclear plant be sure he has Gauss on his machine, and then just get him to name the jpgs or text files he wants sent back to the CIA as 'special.jpg' - Gauss nabs them, sends it back through the network of gauss infected machines, and hey presto - deniable, encrypted, distributed Dead Drops. Wow. Clever. Thank you

Clever. The font makes it possible for the agent to verify he is on a Gauss machine by visiting seemingly innocuous websites which have code to detect whether the font exists, and then inform him by outputting special text only he knows about. He could receive messages that way too. Once he knows it's a Gauss machine, he can drop his specially named files and they are delivered.

Is the idea that gauss would act like a secret file katamari, rolling around collecting data while it spreads, and being harvested when it "infects" a creator controlled machine? It would seem like any direct data transmission would be detectable and investigated with extreme prejudice.

Re: The Mystery of the Encrypted Gauss Payload

#25

Post by sirclueless »

danielweber wrote: post #20
sounds wrote: post #15

Earlier quoted context omitted.

The full implications of this code are that the attacker already has another channel to access your machine. It's not much consolation that you now know that you're being targeted by the Program Files entries (they're a major pain to rename). It's likely there are one or more plants inside your operation and they have physical access to the machine, which is considered game over.

Getting a certain filename onto your computer doesn't sound like a hard problem. Just send them a mail with an attachment of "398rgf90rej243rf.htm" that their email client helpfully extracts for them, or have a file with that name in their web cache when they browse the internet.

Well, Gauss requires a file in %PROGRAMFILES% which is considerably more difficult to plant.

Re: The Mystery of the Encrypted Gauss Payload

#26

Post by kayge »

"the attackers are looking for a very specific program with the name written in an extended character set, such as Arabic or Hebrew, or one that starts with a special symbol such as “~”."

I suppose µTorrent is too obvious... Anyway, these kinds of mysteries help re-ignite my interest in Cryptography. I'd love to hear feedback from a fellow HNer about the course from Udacity (perhaps via email since it will probably be considered off-topic here).

Re: The Mystery of the Encrypted Gauss Payload

#27

Post by [deleted] »

raverbashing wrote: post #6
jgrahamc wrote: post #2

The core of this is 'find X' such that md5(md5(...10,000 times...(md5(X + salt)...)) = hash where salt and hash are known. X is derived from the names of programs existing on a Windows machine with a particular format. Or, find a way to calculate md5(md5(...10,000 times...(md5(X + salt')...)) given that hash is known and salt' but X is not. Or alternatively, attempt a known plain text attack against RC4. Given that a…

Well, wasn't MD5 broken? It should be possible to do a brute force search using a couple of days of EC2 or (insert your favorite cloud provider) here. And by bruteforce you can try text search, or just go for the raw bytes. Not sure a collision can work in this case as well.

[deleted]

Re: The Mystery of the Encrypted Gauss Payload

#28

Post by tedunangst »

raverbashing wrote: post #8
jgrahamc wrote: post #7

Earlier quoted context omitted.

To recover X + salt you'd be looking at a preimage attack of MD5. I am only aware of one preimage attack against MD5 and it's only theoretical. The input to the RC4 key generator is an MD5 hash which means you'd be looking at doing a brute force attack against an input of 2^128 bits. Assuming you find the answer on average in 2^127 and you are looking at an enormous search space. According to a recent article EC2 has…

I'd try to bruteforce X (to match the hash), not RC4 at first (though it may be easier) PBKDF2 is SHA-1 and 4096 rounds, this shouldn't be impossible Bonus points if you use FPGAs to calculate MD5s

PBKDF2 uses a hash function which need not be SHA-1 and applies it a variable number of rounds with a recommended minimum of 1000.

Re: The Mystery of the Encrypted Gauss Payload

#29

Post by [deleted] »

mkup wrote: post #10

It looks like it would be easier to bruteforce fixed RC4 key than 10000 iterations of MD5, especially due to known weaknesses of RC4 key schedule. Name of target software in Program Files is interesting nevertheless. Probably it's mentioned in the encrypted code/data.

[deleted]

Re: The Mystery of the Encrypted Gauss Payload

#30

Post by eli »

ceautery wrote: post #12

The article mentions "~" as a possible starting point, but "{" is also greater than 7A, which would match all the "InstallShield Installation Information" subfolders.

Great point... are those uniquely named based on the application installed? That might be a nice, oblique way of checking if a particular program is installed.
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