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The Mystery of the Encrypted Gauss Payload

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Re: The Mystery of the Encrypted Gauss Payload

#31

Post by eli »

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.

Why would you need to trick someone into saving a file with a particular name? You already have malware running on their machine!

Seems much more likely that the check is there to confirm that the payload only runs on specific targets. And, perhaps more importantly, to make recovery and dissection of the payload very difficult for someone without access to the target(s).

Re: The Mystery of the Encrypted Gauss Payload

#32

Post by praptak »

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.

Even with a reverse-md5^10000 oracle, you'd only get some bits that hash to the same hash as the mysterious pair of strings. Unfortunately the decryption key is derived from the pair of strings themselves, not from their hash. Reverting md5 is not enough to retrieve the decryption key.

Re: The Mystery of the Encrypted Gauss Payload

#33

Post by Achshar »

kayge wrote: post #26

"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 b…

I thought about uTorrent too, but Mu has a hex of 0x03BC. Plus it is a popular software and in windows, it's folder in program files uses 'u' instead of Mu.

http://www.fileformat.info/info/unicode/char/3bc/index.htm

Re: The Mystery of the Encrypted Gauss Payload

#34

Post by lt »

eli wrote: post #30
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.

Yes, these are GUIDs in the following format:

{931373E2-3DA4-4631-930C-F59510630DA3}

It seems to me that's a good theory of what it might be looking for, as GUIDs should make good triggers. I wonder if this reduces the search space enough to make brute force feasible now.

Re: The Mystery of the Encrypted Gauss Payload

#35

Post by mtkd »

jgrahamc wrote: post #7
raverbashing wrote: post #6

Earlier quoted context omitted.

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.

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…

What about sourcing all known \Program Files\ paths out of search engine indexes which meet the criteria and brute forcing.

Microsoft exception reporting must have a list of all apps ever seen too?

Re: The Mystery of the Encrypted Gauss Payload

#36

Post by Zarathust »

lt wrote: post #34
eli wrote: post #30

Earlier quoted context omitted.

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.

Yes, these are GUIDs in the following format: {931373E2-3DA4-4631-930C-F59510630DA3} It seems to me that's a good theory of what it might be looking for, as GUIDs should make good triggers. I wonder if this reduces the search space enough to make brute force feasible now.

To bruteforce like this, wouldn't you need every possible application installed on the computer?

If the payload is a zero day for an obscure Iranian made piece of software, no one will ever get that

Re: The Mystery of the Encrypted Gauss Payload

#38

Post by raverbashing »

mtkd wrote: post #35
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…

What about sourcing all known \Program Files\ paths out of search engine indexes which meet the criteria and brute forcing. Microsoft exception reporting must have a list of all apps ever seen too?

There is one aspect there that may or may not be important

I don't know if the "Program files" path (or the full path) is added to the hash calculation, but at least in Windows XP this is localized

Or who knows, the secret is that it only works in systems where Program files is in D:/

Re: The Mystery of the Encrypted Gauss Payload

#39

Post by tjic »

orenmazor wrote: post #3

I just imagined the author reading that post and smirking to themselves.

My thought exactly - how weird it must be to be inside looking out.

Public key crypto was discovered on the inside long before it was rediscovered on the outside, and I figure that the insiders must have been amused by Diffie, Hellman, R, S, and A.

--------

http://en.wikipedia.org/wiki/Public-key_cryptography#History

In 1997, it was publicly disclosed that asymmetric key algorithms were developed by James H. Ellis, Clifford Cocks, and Malcolm Williamson at the Government Communications Headquarters (GCHQ) in the UK in 1973.[4] These researchers independently developed Diffie–Hellman key exchange, and a special case of RSA. The GCHQ cryptographers referred to the technique as "non-secret encryption". This work was named an IEEE Milestone in 2010.[5]

Re: The Mystery of the Encrypted Gauss Payload

#40

Post by tjic »

meatsock wrote: post #37

a good point raised in the comments is that the "arabic or hebrew" part really meant to say a "non-letter us-ascii value including curley brackets, tilde, and pipe". not sure why anyone would want to jump the gun on narrowing down geography in this way.

> not sure why anyone would want to jump the gun on narrowing down geography in this way.

Because it's a tool designed to take out Iranian uranium refining tools.

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