PHP working on new patch for critical vulnerability after initial one failed

Upcoming PHP updates will address two known remote code execution vulnerabilities

The PHP Group plans to release new versions of the PHP processor on Tuesday in order to patch two publicly known critical remote code execution vulnerabilities, one of which was improperly addressed in a May 3 update.

One of the vulnerabilities is known as CVE-2012-1823 and is located in php-cgi, a component that allows PHP to run in a Common Gateway Interface (CGI) configuration. It was discovered and reported privately to the PHP Group in mid-January by a team of computer security enthusiasts called De Eindbazen.

The bug allows for URL query strings that contain the "-" character to be interpreted by the php-cgi binary as command line switches, such as -s, -d, -c. The vulnerability can be exploited to disclose source code from PHP scripts or to remotely execute arbitrary code on vulnerable systems.

On May 3, the PHP Group released PHP 5.3.12 and PHP 5.4.2 as emergency updates in order to address the remote code execution flaw after technical details about it were accidentally made public.

However, shortly afterward, Stefan Esser, the creator of the Suhosin PHP security extension, and other security experts pointed out via Twitter that the CVE-2012-1823 fix included in PHP 5.3.12 and PHP 5.4.2 can easily be bypassed.

The PHP Group acknowledged the ineffectiveness of its original patch on Sunday and announced plans to release new updates on Tuesday. "These [upcoming] releases will fix the CGI flaw and another CGI-related issue in apache_request_header (5.4 only)," the PHP developers wrote.

The announcement also included a workaround for CVE-2012-1823 based on Apache's mod_rewrite module that can be used to block queries containing "-". However, the workaround's generic rewrite conditions could end up blocking legitimate queries like "?top-40" as well, so every Web server administrator needs to alter the workaround to fit their particular needs.

The second issue to be patched on Tuesday, which involves the apache_request_header, is a heap buffer overflow vulnerability that can also be exploited for remote code execution, Georg Wicherski, the malware analyst and exploit developer who discovered it, said Friday on Twitter.

In follow-up tweets Wicherski explained how the vulnerability can be exploited and posted a link to a patch that has been sent to the PHP developers for review several weeks ago.

Esser believes that not getting patches right the first time and being forced to release new ones for the same vulnerability can create confusion among users. The security researcher took issue with the fact that the PHP Group did not post an alert quicker on the front page to alert users that the PHP 5.3.12 and PHP 5.4.2 updates were broken.

A Web server admin who installs one of those updates and then sees a warning about the vulnerability on a news website the following day, might think that he already has the problem covered, he said Friday on Twitter.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments


James Cook University - Master of Data Science Online Course

Learn more >


Victorinox Werks Professional Executive 17 Laptop Case

Learn more >



Back To Business Guide

Click for more ›

Brand Post

Most Popular Reviews

Latest Articles


PCW Evaluation Team

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Walid Mikhael

Brother QL-820NWB Professional Label Printer

It’s easy to set up, it’s compact and quiet when printing and to top if off, the print quality is excellent. This is hands down the best printer I’ve used for printing labels.

Ben Ramsden

Sharp PN-40TC1 Huddle Board

Brainstorming, innovation, problem solving, and negotiation have all become much more productive and valuable if people can easily collaborate in real time with minimal friction.

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?