MyCERT Advisories

MyCERT Advisories, Alerts and Summaries for the year 2012
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MA-295.022012 : MyCERT Alert - Multiple Critical Vulnerabilities in PHP

Date first published: 2012-02-04

1.0 Introduction

Multiple vulnerabilities have been reported in PHP, which can be exploited to cause a Denial of Service (DoS) and allow a remote attacker to execute arbitrary code on a vulnerable system.

The Hash Collision Denial of Service vulnerability (CVE-2011-4885) is caused due to an error within a hash generation function when hashing form posts and updating a hash table. This can be exploited to cause a hash collision resulting in high CPU consumption via a specially crafted form sent in a HTTP POST request.

The arbitrary remote code execution vulnerability (CVE-2012-0830), exist due to the improper patch released for CVE-2011-4885 with the poor implementation of "max_input_var" introduced in PHP 5.3.9

2.0 Impact

By exploiting these vulnerabilities, it allows a remote attacker to crash the web server that is running PHP or potentially execute code on it. [1][2]

3.0 Affected Products

  • Hash collision denial of service vulnerability (CVE-2011-4885)
    • PHP 5.3.8 and prior

  • Arbitrary remote code execution vulnerability (CVE-2012-0830)
    • PHP 5.3.9

4.0 Recommendation

Users are recommended to upgrade to PHP 5.3.10, which has properly fix both vulnerabilities mention above.

Additionally, users are also recommended to enable Suhosin if at all possible. More information on Suhosin can be obtained here:

Users with mod_security may refer to SpiderLabs's blog post on the mitigation for the DOS vulnerability (if PHP upgrade is not possible)

Generally, MyCERT advises the users of this software to be updated with the latest security announcements by the vendor. For any enquiries, MyCERT can be reached through the following channels:

E-mail : mycert@mycert.org.my
Phone : 1-300-88-2999 (monitored during business hours)
Fax : +603 89453442
Handphone : +60 19 2665850 (24x7 call incident reporting)
SMS : CYBER999 REPORT <EMAIL> <COMPLAINT> to 15888
Business Hours : Mon - Fri 08:30 -17:30 MYT
Web: http://www.mycert.org.my

5.0 References