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Date: Tue, 1 Jan 2013 23:53:02 +0100
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: dynamic format bug (was: A few questions regarding the newly added BLAKE2 format)
On 1 Jan, 2013, at 23:28 , magnum <john.magnum@...hmail.com> wrote:
> On 1 Jan, 2013, at 22:48 , magnum <john.magnum@...hmail.com> wrote:
>> You are right. Here is a normal md5 hash written twice:
>>
>> $ echo 8ad8757baa8564dc136c1e07507f4a988ad8757baa8564dc136c1e07507f4a98 >test
>> $ ../run/john test -form:dynamic_0
>> Loaded 1 password hash (dynamic_0: md5($p) (raw-md5) [128/128 SSE2 intrinsics 10x4x3])
>> test3 (?)
>> guesses: 1 time: 0:00:00:00 DONE (Tue Jan 1 22:10:20 2013) c/s: 360000 trying: 3533 - sierra
>>
>> Even worse, the overlong hash is stored in john.pot:
>> $ cat ../run/john.pot
>> $dynamic_0$8ad8757baa8564dc136c1e07507f4a988ad8757baa8564dc136c1e07507f4a98:test3
>>
>> And that has this effect:
>> $ ../run/john test -form:dynamic_0 -show
>> 0 password hashes cracked, 1 left
>
> This partly fixes the problem:
>
> diff --git a/src/dynamic_fmt.c b/src/dynamic_fmt.c
> index cf88409..ee14fcb 100644
> --- a/src/dynamic_fmt.c
> +++ b/src/dynamic_fmt.c
> @@ -701,7 +701,7 @@ static int valid(char *ciphertext, struct fmt_main *pFmt)
> if (atoi16[ARCH_INDEX(cp[i])] == 0x7f)
> return 0;
> }
> - if ( (pPriv->pSetup->flags&MGF_SALTED) == 0)
> + if (!cp[cipherTextLen] && (pPriv->pSetup->flags&MGF_SALTED) == 0)
> return 1;
>
> if (cp[cipherTextLen] && cp[cipherTextLen] != '$')
>
>
> After this and using DynamicAlwaysUseRawHashes=Y, only dynamic_19, dynamic_80 and dynamic_100 will accept a 128 character hash. But dynamic_19 is CiscoPIX so that is still wrong. Also, some thin formats fail with this:
>
> Benchmarking: PHPS md5(md5($pass).$salt) [128/128 SSE2 intrinsics 10x4x3]... FAILED (valid)
> Benchmarking: MediaWiki md5($s.'-'.md5($p)) [128/128 SSE2 intrinsics 10x4x3]... FAILED (valid)
> Benchmarking: osCommerce md5($salt.$pass) [128/128 SSE2 intrinsics 10x4x3]... FAILED (valid)
> Benchmarking: phpass MD5 ($P$9) [128/128 SSE2 intrinsics 4x4x3]... FAILED (valid)
>
> So there's more to it.
I'll take that back: The patch is OK. The thin problems were due to still having DynamicAlwaysUseRawHashes=Y in john.conf. Apparently that is flakey even without my patch. I will commit the above. We still need a better valid() for dynamic_19 but that is a separate problem.
magnum
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