NetKit-telnetd: buffer overflows in telnet and telnetd

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200410-03 / netkit-telnetd
Release Date	October 05, 2004
Latest Revision	October 05, 2004: 01
Impact	high
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
net-misc/netkit-telnetd	<= 0.17-r3	>= 0.17-r4	All supported architectures

Related bugreports: #64632

Synopsis

Buffer overflows exist in the telnet client and daemon provided by netkit-telnetd, which could possibly allow a remote attacker to gain root privileges and compromise the system.

2. Impact Information

Background

NetKit-telnetd is a standard Linux telnet client and server from the NetKit utilities.

Description

A possible buffer overflow exists in the parsing of option strings by the telnet daemon, where proper bounds checking is not applied when writing to a buffer. Additionaly, another possible buffer overflow has been found by Josh Martin in the handling of the environment variable HOME.

Impact

A remote attacker sending a specially-crafted options string to the telnet daemon could be able to run arbitrary code with the privileges of the user running the telnet daemon, usually root. Furthermore, an attacker could make use of an overlong HOME variable to cause a buffer overflow in the telnet client, potentially leading to the local execution of arbitrary code.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All NetKit-telnetd users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge sync
# emerge -pv ">=net-misc/netkit-telnetd-0.17-r4"
# emerge ">=net-misc/netkit-telnetd-0.17-r4"

4. References

Page updated October 05, 2004

Summary: This is a Gentoo Linux Security Advisory

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