J-Security Center

Title: Stellar-X MSNTAuth Syslog Format String Vulnerability

Severity: CRITICAL

Description:

Stellar-X MSNTAuth is an authentication module for the Squid web proxy server. It will allow Squid to authenticate users on an NT domain. MSNTAuth is shipped as part of Squid but is not enabled by default.

It has been reported that MSNTAuth is vulnerable to a remotely exploitable format string vulnerability in its internal logging facility. Data that may be externally supplied is passed to syslog() as the format string argument.

By using format specifiers such as '%n', attackers may be able to cause arbitrary locations in memory to be overwritten with almost any value. It may be possible to replace or corrupt critical values such as function pointers or return addresses.

To exploit this, an attacker must insert the malicious format specifiers into a log message. This may be possible for remote, unauthenticated attackers via logging of values such as username, hostname, etc.

This vulnerability may allow for an unauthenticated remote attacker to gain root privileges on the target host.

Affected Products:

  • National Science Foundation Squid Web Proxy 2.0.0
  • National Science Foundation Squid Web Proxy 2.1.0
  • National Science Foundation Squid Web Proxy 2.2.0
  • National Science Foundation Squid Web Proxy 2.3.0
  • National Science Foundation Squid Web Proxy 2.4.0
  • Stellar-X Software MSNTAuth 2.0.0

References:

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