[arch-security] [ASA-201509-4] openldap: denial of service

[Levente Polyak]

Arch Linux Security Advisory ASA-201509-4
=========================================

Severity: High
Date    : 2015-09-12
CVE-ID  : CVE-2015-6908
Package : openldap
Type    : denial of service
Remote  : Yes
Link    : https://wiki.archlinux.org/index.php/CVE

Summary
=======

The package openldap before version 2.4.42-2 is vulnerable to a remote
denial of service.

Resolution
==========

Upgrade to 2.4.42-2.

# pacman -Syu "openldap>=2.4.42-2"

The problem has been fixed upstream but no release is available yet.

Workaround
==========

None.

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

By sending a crafted packet, an attacker can cause the OpenLDAP daemon
to crash with a SIGABRT. This is due to an assert() call within the
ber_get_next method (io.c line 682) that is hit when decoding tampered
BER data.
The following proof of concept exploit can be used to trigger the condition:

# echo "/4SEhISEd4MKYj5ZMgAAAC8=" | base64 -d | nc -v 127.0.0.1 389

The above causes slapd to abort as follows when running with '-d3',
however it should be noted that this will crash the server even when
running in daemon mode.

Impact
======

A remote attacker is able to send specially crafted packets that cause
the OpenLDAP server to crash, leading to denial of service.

References
==========

http://www.openldap.org/its/index.cgi/Software%20Bugs?id=8240
http://www.openldap.org/devel/gitweb.cgi?p=openldap.git;a=commitdiff;h=6fe51a9ab04fd28
https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6908
https://bugs.archlinux.org/task/46265

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