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Add BUG_SSH2_DERIVEKEY, present (according to OpenSSH) in ssh.com

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versions 2.0.*, and causing the shared secret not to be included in
key derivation hashes. (This doesn't quite cause a blatant security
hole because the session ID - _derived_ from the shared secret - is
still included.)

[originally from svn r1853]
This commit is contained in:
Simon Tatham 2002-08-18 09:27:15 +00:00
parent 67cb02d03d
commit c24016e0da
1 changed files with 15 additions and 2 deletions
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13
ssh.c
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@ -182,6 +182,7 @@ static const char *const ssh2_disconnect_reasons[] = {
#define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4 #define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4
#define BUG_CHOKES_ON_RSA 8 #define BUG_CHOKES_ON_RSA 8
#define BUG_SSH2_RSA_PADDING 16 #define BUG_SSH2_RSA_PADDING 16
#define BUG_SSH2_DERIVEKEY 32
static int ssh_pkt_ctx = 0; static int ssh_pkt_ctx = 0;
@ -1701,6 +1702,16 @@ static void ssh_detect_bugs(char *vstring)
logevent("We believe remote version has SSH2 HMAC bug"); logevent("We believe remote version has SSH2 HMAC bug");
} }
if (!strncmp(imp, "2.0.", 4)) {
/*
* These versions have the key-derivation bug (failing to
* include the literal shared secret in the hashes that
* generate the keys).
*/
ssh_remote_bugs |= BUG_SSH2_DERIVEKEY;
logevent("We believe remote version has SSH2 key-derivation bug");
}
if ((!strncmp(imp, "OpenSSH_2.", 10) && imp[10]>='5' && imp[10]<='9') || if ((!strncmp(imp, "OpenSSH_2.", 10) && imp[10]>='5' && imp[10]<='9') ||
(!strncmp(imp, "OpenSSH_3.", 10) && imp[10]>='0' && imp[10]<='2')) { (!strncmp(imp, "OpenSSH_3.", 10) && imp[10]>='0' && imp[10]<='2')) {
/* /*
@ -3497,6 +3508,7 @@ static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr,
SHA_State s; SHA_State s;
/* First 20 bytes. */ /* First 20 bytes. */
SHA_Init(&s); SHA_Init(&s);
if (!(ssh_remote_bugs & BUG_SSH2_DERIVEKEY))
sha_mpint(&s, K); sha_mpint(&s, K);
SHA_Bytes(&s, H, 20); SHA_Bytes(&s, H, 20);
SHA_Bytes(&s, &chr, 1); SHA_Bytes(&s, &chr, 1);
@ -3504,6 +3516,7 @@ static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr,
SHA_Final(&s, keyspace); SHA_Final(&s, keyspace);
/* Next 20 bytes. */ /* Next 20 bytes. */
SHA_Init(&s); SHA_Init(&s);
if (!(ssh_remote_bugs & BUG_SSH2_DERIVEKEY))
sha_mpint(&s, K); sha_mpint(&s, K);
SHA_Bytes(&s, H, 20); SHA_Bytes(&s, H, 20);
SHA_Bytes(&s, keyspace, 20); SHA_Bytes(&s, keyspace, 20);