BID:1955

Multiple Vendor telnetd Remote Denial of Service Vulnerability

Info

Multiple Vendor telnetd Remote Denial of Service Vulnerability

Bugtraq ID:	1955
Class:	Failure to Handle Exceptional Conditions
CVE:
Remote:	Yes
Local:	No
Published:	Nov 14 2000 12:00AM
Updated:	Nov 14 2000 12:00AM
Credit:	Discovered by Jouko Pynnönen <[email protected]> and posted to Bugtraq on Oct 9, 2000.
Vulnerable:	FreeBSD FreeBSD 4.1.1 -STABLE FreeBSD FreeBSD 4.1.1 FreeBSD FreeBSD 4.1 FreeBSD FreeBSD 4.0 alpha FreeBSD FreeBSD 4.0 FreeBSD FreeBSD 3.5 FreeBSD FreeBSD 3.4 FreeBSD FreeBSD 3.3 FreeBSD FreeBSD 3.2 FreeBSD FreeBSD 3.1 FreeBSD FreeBSD 3.0

Not Vulnerable:

Discussion

Multiple Vendor telnetd Remote Denial of Service Vulnerability

Telnetd is a commonly used remote-access server program for unix systems. The version of telnetd that ships with FreeBSD (likely other BSDs at least but uncomfirmed) contains a vulnerability that may allow a malicious remote attacker to cause a denial of service on the victim host.

The TERMCAP telnet variable that is part of client-server negotiations can tell telnetd to search the filesystem for files containing termcap entries. A remote client can cause telnetd to search/read files anywhere on the filesystem via this variable, using I/O resources. Since this is performed before any authentication and telnetd is spawned by inetd, many telnetd processes could be started by an attacker each searching and reading files from the filesystem. This could theoretically result in an exhaustion of system resources.

If exploited this might cause a denial of service on the victim host.

Exploit / POC

Multiple Vendor telnetd Remote Denial of Service Vulnerability

Currently the SecurityFocus staff are not aware of any exploits for this issue. If you feel we are in error or are aware of more recent information, please mail us at: [email protected].

Solution / Fix

Multiple Vendor telnetd Remote Denial of Service Vulnerability

Solution:
FreeBSD has released a patch for telnetd that corrects this vulnerability.

FreeBSD FreeBSD 3.0