[ GLSA 200408-19 ] courier-imap: Remote Format String Vulnerability

[GLSA]

Gentoo Linux Security Advisory

Title: courier-imap: Remote Format String Vulnerability (GLSA 200408-19)
Severity: high
Exploitable: remote
Date: August 19, 2004
Updated: May 22, 2006
Bug(s): #60865
ID: 200408-19

Synopsis

There is a format string vulnerability in non-standard configurations of courier-imapd which may be exploited remotely. An attacker may be able to execute arbitrary code as the user running courier-imapd (oftentimes root).

Background

Courier-IMAP is an IMAP server which is part of the Courier mail system. It provides access only to maildirs.

Affected Packages

Package: net-mail/courier-imap
Vulnerable: <= 3.0.2-r1
Unaffected: >= 3.0.5
Architectures: All supported architectures


Description

There is a format string vulnerability in the auth_debug() function which can be exploited remotely, potentially leading to arbitrary code execution as the user running the IMAP daemon (oftentimes root). A remote attacker may send username or password information containing printf() format tokens (such as "%s"), which will crash the server or cause it to execute arbitrary code. This vulnerability can only be exploited if DEBUG_LOGIN is set to something other than 0 in the imapd config file.

Impact

If DEBUG_LOGIN is enabled in the imapd configuration, a remote attacker may execute arbitrary code as the root user.

Workaround

Set the DEBUG_LOGIN option in /etc/courier-imap/imapd to 0. (This is the default value.)

Resolution

All courier-imap users should upgrade to the latest version: