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Date: Thu, 31 Dec 2015 09:14:45 -0600
From: jfoug <jfoug@...nwall.net>
To: john-users@...ts.openwall.com, ls@...r.so
Subject: Re: QNX Neutrino 6.6.0 password hashes
I have been able to get 'correct' hash value for a 99 iteration password
'3' for sha512. I am using my 'generic' sha512 code. I made a tiny
change within sha512_final
```C
void jtr_sha512_final(void *_output, jtr_sha512_ctx *ctx)
{
ARCH_WORD_32 last, padcnt;
ARCH_WORD_64 bits;
union {
ARCH_WORD_64 wlen[2];
unsigned char mlen[16]; // need aligned on sparc
} m;
unsigned char *output = (unsigned char *)_output;
bits = (ctx->total << 3);
m.wlen[0] = 0;
OUTBE64(bits, m.mlen, 8);
last = ctx->total & 0x7F;
padcnt = (last < 112) ? (112 - last) : (240 - last);
jtr_sha512_update(ctx, (unsigned char *) padding, padcnt);
+ //m.mlen[0] = '3';
+ //m.mlen[1] = '3';
+ //m.mlen[2] = '3';
+ //m.mlen[3] = '3';
+ m.mlen[4] = 0x80;
jtr_sha512_update(ctx, m.mlen, 16);
// ....
```
So, by placing a 0x80 into the location where the 0x80 'would' have been
placed in the first buffer, I get the same hash. So this looks like a
'classic' off by one bug within the QNX code. They are cleaning the
buffer, BUT forgetting about the 0x80 byte 'added'. Why 112, 113 and 114
length hashes are working, is beyond me. Likely, this is not the only
bug, but it lets me continue to look.
On 12/31/2015 8:36 AM, jfoug wrote:
> A new test was performed, using just a 1 byte password and 16 byte
> salt. It appears that hashes (salt+passwords) up to 114 bytes 'work',
> but after that, they are broken (but consistently broken) for sha512.
> It may be that the buffer cleaning is not being properly done (the
> final 'bit length' buffer). Hopefully this can be figured out, and
> replicated, so that sha512 can also be cracked by jtr. It is
> especially important, since sha512 is the 'default'
>
> https://moar.so/tmp/qnx_sha512_broken_2.txt
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