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Date: Tue, 1 Jan 2013 23:28:35 +0100
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: dynamic format bug (was: A few questions regarding the newly added BLAKE2 format)
On 1 Jan, 2013, at 22:48 , magnum <john.magnum@...hmail.com> wrote:
> On 1 Jan, 2013, at 21:56 , Frank Dittrich <frank_dittrich@...mail.com> wrote:
>> The dynamic formats also accept these hashes when using
>> --format=dynamic_0 (or dynamic_2, dynamic_3, dynamic_19, ...).
>
> 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. Jim, are you reading this?
magnum
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