Vulnerability Alert

PHP Hash Collisions Fix Regression max_input_vars Arbitrary Code Execution Vulnerability

 
Threat Type:CWE-94: Code Injection
IntelliShield ID:25100
Version:6
First Published:2012 February 03 14:43 GMT
Last Published:2012 August 23 17:14 GMT
Port: Not available
CVE:CVE-2012-0830
BugTraq ID:51830
Urgency:Possible use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:7.5 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:5.9
 
Version Summary:

HP has re-released a security bulletin and updated software to address the PHP hash collisions fix regression max_input_vars arbitrary code execution vulnerability.

 
 
Description

PHP 5.3.9 contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code or cause a denial of service (DoS) condition on the affected system.

The vulnerability is due to a regression error in the PHP 5.3.9 update. The update introduced the error with the addition of the max_input_vars directive, which is intended to prevent hash collision attacks. An unauthenticated, remote attacker could exploit the vulnerability by sending malicious requests to the affected PHP-based application. If successful, the attacker could execute arbitrary code or cause a DoS condition on the targeted system

Proof-of-concept code that demonstrates an exploit of this vulnerability is publicly available.

PHP has confirmed this vulnerability and released updated software.

 
Warning Indicators

PHP version 5.3.9 is vulnerable.

 
IntelliShield Analysis

PHP is widely utilized for many web applications and has a large installation base. The regression error that introduces the vulnerability was part of a security update to the affected software. Because the version update was a recommended security update, the vulnerability may exist on a large number of web servers.

Proof-of-concept code is publicly available, increasing the likelihood of attack.

 
Vendor Announcements

PHP has published release announcements at the following link: PHP 5.3.10 Release Announcement 

Apple has released a security advisory at the following link: HT5281

FreeBSD has released a VuXML document at the following link: php -- arbitrary remote code execution vulnerability

HP has released security bulletins c03368475 and c03360041 at the following links: HPSBUX02791 SSRT100856 and HPSBMU02786 SSRT100877

Red Hat has released security advisories at the following links: RHSA-2012:0092 and RHSA-2012:0093-01

 
Impact

An unauthenticated, remote attacker could execute arbitrary code with the privileges of the web server. This could allow the attacker to modify and view files with web server privileges or create a DoS condition on the affected system, denying access to legitimate users.

 
Technical Information

The vulnerability is due to an implementation flaw in the code that handles the hashing functionality in the affected software. PHP 5.3.9 implemented a fix to remediate a hash collision DoS condition. The fix implemented the new directive max_input_vars in the PHP configuration file php.ini, and corresponding updates to the function php_register_variable_ex() in the php_variables.c source code file. The new code performs improper boundary checks.

An unauthenticated, remote attacker could exploit the vulnerability by sending HTTP requests that contain a number of variables that exceed the value defined in max_input_vars and that include an array with malicious code to an affected PHP-based application. Processing the input could result in arbitrary code execution in the security context of the web server or cause a DoS condition.

 
Safeguards

Administrators are advised to apply the appropriate updates.

Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.

Administrators are advised to monitor affected systems.

 
Patches/Software

PHP has released updated versions at the following links: PHP 5.3.10 

Apple has released updated software at the following links:

OS X Lion Update 10.7.4 (Client)
OS X Lion Update 10.7.4 (Server)

CentOS packages can be updated using the up2date or yum command.

FreeBSD releases ports collection updates at the following link: Ports Collection Index

HP has released updated software for registered customers at the following links:

Apache Web Server Suite 3.24 for HP-UX
B.11.23 HPUXWS22ATW-B324-32
B.11.23 HPUXWS22ATW-B324-64
B.11.31 HPUXWS22ATW-B324-32
B.11.31 HPUXWS22ATW-B324-64

Apache Web Server Suite 2.36 for HP-UX
B. 11.11 HPUXWSATW-B236-1111

HP has released updated software at the following links:

HP System Management Homepage 7.1.1 for Windows x64
HP System Management Homepage 7.1.1 for Windows x86
HP System Management Homepage 7.1.1 for Linux (AMD64/EM64T)
HP System Management Homepage 7.1.1 for Linux (x86)

Red Hat packages can be updated using the up2date or yum command.

 
Alert History
 

Version 5, June 29, 2012, 8:59 PM: HP has released an additional security bulletin and updated software to address the PHP hash collisions fix regression max_input_vars arbitrary code execution vulnerability.

Version 4, June 15, 2012, 10:16 AM: HP has released a security bulletin and updated software to address the PHP hash collisions fix regression max_input_vars arbitrary code execution vulnerability.

Version 3, May 10, 2012, 11:03 AM: Apple has released a security advisory and updated software to address the PHP hash collisions fix regression max_input_vars arbitrary code execution vulnerability.

Version 2, February 6, 2012, 12:18 PM: FreeBSD has released a VuXML document and updated ports collection to address the PHP hash collisions fix regression max_input_vars arbitrary code execution vulnerability.

Version 1, February 3, 2012, 9:43 AM: PHP contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code or cause a denial of service condition. Updates are available.



Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
phpphp 5.3.9 Base

Associated Products:
AppleMac OS X 10.7 Base | 10.7.1 Base | 10.7.2 Base | 10.7.3 Base
AppleMac OS X Server 10.7 Base | 10.7.1 Base | 10.7.2 Base | 10.7.3 Base
CentOS ProjectCentOS 4 .0 i386, .0 x86_64, .0 ia64, .0 s390x, .1 i386, .1 x86_64, .1 ia64, .1 s390x, .2 i386, .2 x86_64, .2 ia64, .2 s390x, .3 i386, .3 x86_64, .3 ia64, .3 s390x, .4 i386, .4 x86_64, .4 ia64, .4 s390x, .5 i386, .5 x86_64, .5 ia64, .5 s390x, .6 i386, .6 x86_64, .6 ia64, .6 s390x, .7 i386, .7 x86_64 | 5 .0 i386, .0 x86_64, .1 i386, .1 x86_64, .2 i386, .2 x86_64, .3 i386, .3 x86_64, .4 i386, .4 x86_64, .5 i386, .5 x86_64 | 6 .0 i386, .0 x86_64, .1 i386, .1 x86_64, .2 i386, .2 x86_64
FreeBSD ProjectFreeBSD 6.3 Base | 6.4 Base | 7.0 Base | 7.1 Base | 7.2 Base | 7.3 Base | 7.4 Base | 8.0 Base | 8.1 Base | 8.2 Base | 9.0 Base
HPHP-UX 11.11/11i Base | 11.23 Base | 11.31 Base
HPHP-UX Web Server Suite (HPUXWSSUITE) 2.0 Base | 2.22 Base | 2.33 Base | 2.34 Base | 2.35 Base | 3.0 Base | 3.12 Base | 3.13 Base | 3.14 Base | 3.15 Base | 3.17 Base | 3.18 Base | 3.19 Base | 3.20 Base | 3.21 Base | 3.22 Base | 3.23 Base
HPSystem Management Homepage (SMH) 6.0.0 Base | 6.1 Base | 6.2 Base | 7.0 Base | 7.1 Base
Red Hat, Inc.Red Hat Desktop 4 IA-32, x86_64
Red Hat, Inc.Red Hat Enterprise Linux 5 IA-32, IA-64, PPC, ppc64, s390, s390x, x86_64
Red Hat, Inc.Red Hat Enterprise Linux Server AUS 6.2 IA-32, x86_64
Red Hat, Inc.Red Hat Enterprise Linux Advanced Server 4 IA-32, IA-64, x86_64, PPC, ppc64, s390, s390x, ppc64iseries
Red Hat, Inc.Red Hat Enterprise Linux Desktop 6 IA-32, x86_64
Red Hat, Inc.Red Hat Enterprise Linux Desktop Workstation 5 IA-32, x86-64
Red Hat, Inc.Red Hat Enterprise Linux Enterprise Server 4 IA-32, IA-64, PPC, PPC64, s390, s390x, x86_64, PPC_64iseries
Red Hat, Inc.Red Hat Enterprise Linux HPC Node 6 x86_64
Red Hat, Inc.Red Hat Enterprise Linux Server 6 IA-32, PPC, PPC 64, s390, s390x, x86_64
Red Hat, Inc.Red Hat Enterprise Linux Server EUS 6.2.z IA-32, PPC, PPC64, s390, s390x, x86_64
Red Hat, Inc.Red Hat Enterprise Linux Workstation 4 IA-32, IA-64, x86_64 | 6 IA-32, x86_64




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