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
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