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Date: Tue, 10 Mar 2015 09:31:16 +0800
From: Kai Zhao <loverszhao@...il.com>
To: john-dev@...ts.openwall.com
Subject: Bug in Siemens-s7 format
Thanks to john-dev's help, I found my first bug in john jumbo.
File: src/siemens-s7-format
Branch: bleeding-jumbo
https://github.com/magnumripper/JohnTheRipper/blob/bleeding-jumbo/src/siemens-s7_fmt_plug.c
_Bug1_
In valid() function from line 89 to 91. The right format of siemens-s7 are
as follows:
"$siemens-s7$1$599fe00cdb61f76cc6e949162f22c95943468acb$002e45951f62602b2f5d15df217f49da2f5379cb"
^
"$siemens-s7$0$387c1fe4ce97e0e71f5a93b4a9557a947cd40d6c$d7789feee651559a09e2f2d92b57306d2835e209"
^
p points to "1" or "0" field.
line 89: outcome = atoi(p);
line 90: if (outcome != 1 && outcome != 0)
line91: goto bail;
I think the author maybe want to check the field to be "1" or "0", but the
code does not meet the need.
Such as formats also pass the check:
"$siemens-s7$AAAAAAA$387c1fe4ce97e0e71f5a93b4a9557a947cd40d6c$d7789feee651559a09e2f2d92b57306d2835e209"
^
"$siemens-s7$###########$387c1fe4ce97e0e71f5a93b4a9557a947cd40d6c$d7789feee651559a09e2f2d92b57306d2835e209"
^
So I think there is a bug for check the field to be "1" or "0"
_Bug2_
According to the valid() function, the hash below can also pass the valid
check.
"$siemens-s7$1$599fe00cdb61f76cc6e949162f22c95943468acb$0"
^
So, there is a bug in get_binary().
line 120: static void *get_binary(char *ciphertext)
line 121: {
line 122: static union {
line 123: unsigned char c[BINARY_SIZE];
line 124: ARCH_WORD dummy;
line 125: } buf;
line 126: unsigned char *out = buf.c;
line 127: char *p;
line 128: int i;
line 129: p = strrchr(ciphertext, '#39;) + 1;
line 130: for (i = 0; i < BINARY_SIZE; i++) {
line 131: out[i] =
line 132: (atoi16[ARCH_INDEX(*p)] << 4) |
line 133: atoi16[ARCH_INDEX(p[1])];
line 134: p += 2;
line 135: }
line 136:
line 137: return out;
line 138: }
In line 129, p points to "0", and BINARY_SIZE is 20. But in line 132 and
133 it tries
to visit *p and p[1], also p += 2, thus it will visit the unknown ares!
_Conclusion_
I think the two bugs can be fixed to add check in valid().
Thanks for those who help me. It is inspiring to find the first bug!
sincerely,
Kai
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