ASAL

kedahan

Over $60 Million Worth of Bitcoins Hacked from NiceHash Exchange. Bitcoin mining platform and exchange NiceHash has been hacked, leaving investors short of close to $68 million in BTC.

As the price of Bitcoin continues to rocket, surging past the $14,500 mark at the time of writing, cyberattackers have once again begun hunting for a fresh target to cash in on in this lucrative industry.

Banks and financial institutions have long cautioned that the volatility of Bitcoin and other cryptocurrency makes it a risky investment, but for successful attackers, the industry potentially provides a quick method to get rich — much to the frustration of investors.

Unfortunately, it seems that one such criminal has gone down this path, compromising NiceHash servers and clearing the company out.

In a press release posted on Reddit, on Wednesday, NiceHash said that all operations will stop for the next 24 hours after their "payment system was compromised and the contents of the NiceHash Bitcoin wallet have been stolen."

NiceHash said it was working to "verify" the precise amount of BTC stolen, but according to a wallet which allegedly belongs to the attacker — traceable through the blockchain — 4,736.42 BTC was stolen, which at current pricing equates to $67,867,781.

"Clearly, this is a matter of deep concern and we are working hard to rectify the matter in the coming days," NiceHash says. "In addition to undertaking our own investigation, the incident has been reported to the relevant authorities and law enforcement and we are co-operating with them as a matter of urgency."

"We are fully committed to restoring the NiceHash service with the highest security measures at the earliest opportunity," the trading platform added.

The company has also asked users to change their online passwords as a precaution. NiceHash says the "full scope" of the incident is unknown.

"We are truly sorry for any inconvenience that this may have caused and are committing every resource towards solving this issue as soon as possible," the company added.

Inconvenience is an understatement — especially as so much was left in a single wallet — but the moment those coins shift, we may know more about the fate of the stolen investor funds.

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kedahan

The remote service ask for a name, if you send more than 64 bytes, a memory leak happens.
The buffer next to the name's is the first random value used to init the srand()

If we get this value, and set our local srand([leaked] ^ [luckyNumber]) we will be able to predict the following randoms and win the game, but we have to see few details more ;)

The function used to read the input until the byte \n appears, but also up to 64 bytes, if we trigger this second condition there is not 0x00 and the print shows the random buffer :)

The nickname buffer:

The seed buffer:

So here it is clear, but let's see that the random values are computed with several gpu instructions which are decompiled incorrectly:

We tried to predict the random and aply the gpu divisions without luck :(

There was a missing detail in this predcitor, but there are always other creative ways to do the things.
We use the local software as a predictor, we inject the leaked seed on the local binary of the remote server and got a perfect syncronization, predicting the remote random values:

The process is a bit ugly becouse we combined automated process of leak exctraction and socket interactive mode, with the manual gdb macro.

The macro:

More info

kedahan

I have developed a fast emulator for modern shellcodes, that perform huge loops of millions of instructions emulated for resolving API or for other stuff.

The emulator is in Rust and all the few dependencies as well, so the rust safety is good for emulating malware.

There are shellcodes that can be emulated from the beginning to the end, but when this is not possible the tool has many features that can be used like a console, a memory tracing, register tracing, and so on.

https://github.com/sha0coder/scemu

In less than two seconds we have emulated 7 millions of instructions arriving to the recv.

At this point we have some IOC like the ip:port where it's connecting and other details.

Lets see what happens after the recv() spawning a console at position: 7,012,204

target/release/scemu -f shellcodes/shikata.bin -vv -c 7012204

In the console, pressing "enter" several times to emulate step into several steps and we arrive to a return instruction.

Let's see the stack in this moment:

The "ret" instruction is going to jump to the buffer read with recv() so is a kind of stager.

The option "-e" or "--endpoint" is not ready for now, but it will allow to proxy the calls to get the next stage automatically, but for now we have the details to get the stage.

SCEMU also identify all the Linux syscalls for 32bits shellcodes:

The encoder used in shellgen is also supported https://github.com/MarioVilas/shellgen

Let's check with cobalt-strike:

We can see where is connecting and which headers is using, so right now we can replicate the communications.

In verbose mode we could do several greps to see the calls and correlate with ghidra/ida/radare or for example grep the branches to study the emulation flow.

target/release/scemu -f shellcodes/rshell_sgn.bin -vv | grep j

target/release/scemu -f shellcodes/rshell_sgn.bin -vv -c 44000 -l

The -l --loops options makes the emulation a bit slower but track the number of iterations.

Is possible to print all the registers in every step with -r or --registers but also is possible to track specific register for example with --reg esi

target/release/scemu -f shellcodes/shikata.bin --reg esi

In this case ESI register points to the API name, if we track EAX or ECX will see that are the counters of the loop. These shellcodes contains a hard loop to locate the API names.

The flag -i or --inspect allow to monitor memory using expressions like "dword ptr [eax + 0xa]"

target/release/scemu -f shellcodes/shikata.bin -i 'dword ptr [esi]'

And more things to come... find a demo below:

https://www.youtube.com/watch?v=qTYmMjW3DFs

ASAL

Wednesday, May 31, 2023

OVER $60 MILLION WORTH OF BITCOINS HACKED FROM NICEHASH EXCHANGE

ASIS CTF Quals 2015 - Sawthis Writeup - Srand Remote Prediction

More info

Tuesday, May 30, 2023

Fast Emulator For Shellcodes In Rust

More articles

Hackerhubb.blogspot.com

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