Berkeley Telnet clients that support encryption can be decrypted easily
| bsd-telnet (516) |  Medium Risk |
Description:
A vulnerability in Berkeley Telnet clients that support encryption and Kerberos V4 authentication substantially reduces the effectiveness of the encryption and can ultimately lead to the session being decrypted.
Platforms Affected:
- WindRiver, BSDOS
Remedy:
Apply the appropriate patch for your system, as listed in CERT Advisory CA-1995-03. See References. If you have an encrypting Telnet from a vendor who is not listed in the Advisory, please contact that vendor for information regarding how to get a fixed version.
For Berkeley SW Distribution (BSDI):
Modify the auth.c, kerberos.c, and commands.c source code with the patch included in CERT Advisory CA-95.03a, Appendix B.
For FTP Software, Inc.:
Encrypting telnet versions (provided in the PC/TCP or OnNet packages) should call the FTP technical support line at 1-800-282-4387 and ask for the "tn encrypt patch.".
For National Center for Supercomputer Applications (NCSA):
Upgrade to the latest version of NCSA Telnet (2.6.1d7 or later) and apply the appropriate Kerberos plug-in, as listed in CERT Advisory CA-1995-03. See References.
Consequences:
Bypass Security
References:
- CERT Advisory CA-1995-03a, Telnet Encryption Vulnerability at http://www.cert.org/advisories/CA-1995-03.html.
- CIAC Information Bulletin F-12, Kerberos Telnet Encryption Vulnerability at http://www.ciac.org/ciac/bulletins/f-12.shtml.
- BID-139: Berkeley Telnet Kerberos Vulnerability
- CVE-1999-1098: Vulnerability in BSD Telnet client with encryption and Kerberos 4 authentication allows remote attackers to decrypt the session via sniffing.
- OSVDB ID: 4881: BSD Telnet Client Kerberos Session Sniffing
Reported:
Mar 01, 1995
The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (IBM Internet Security Systems X-Force) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.
For corrections or additions please email xforce@iss.net