[arch-security] [Arch Linux Security Advisory ASA-201410-5] rsyslog: remote denial of service

[Remi Gacogne]

Arch Linux Security Advisory ASA-201410-5
=========================================

Severity: Medium
Date    : 2014-10-08
CVE-ID  : CVE-2014-3683
Package : rsyslog
Type    : Denial of service
Remote  : Yes
Link    : https://wiki.archlinux.org/index.php/CVE-2014

Summary
=======

The package rsyslog before version 8.4.2-1 is vulnerable to a remote
denial of service.

Resolution
==========

Upgrade to 8.4.2-1.

# pacman -Syu "rsyslog>=8.4.2-1"

The problem has been fixed upstream in version 8.4.2.

Workaround
==========

It is possible to prevent unauthorized remote hosts from sending syslog
messages to vulnerable hosts, for example by using a firewall.

Description
===========

The rsyslog fix shipped in 8.4.1 for an invalid PRI value (see
ASA-201410-1) was incomplete, as it did not cover cases where PRI values
> MAX_INT. These values caused an integer overflow, resulting in
negative values.

Sending a syslog message containing an invalid PRI value to a vulnerable
rsyslog server accepting remote message will trigger a denial of service
by crashing the rsyslog process.

Impact
======

A remote attacker authorized to send syslog messages can cause the
syslog server to segfault, causing a denial of service. According to the
rsyslog project leader, under certain preconditions it may possibly lead
to remote code execution [1]. The default configuration is safe from
these preconditions.

References
==========

[1] http://www.rsyslog.com/remote-syslog-pri-vulnerability-cve-2014-3683/
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-3683


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