The developers of PHP have released updates to thwart fresh attacks against systems that use the scripting language to dynamically generate web pages.
All users are encouraged to upgrade to PHP 5.4.3 or PHP 5.3.13, as appropriate, after a serious security bug in PHP-CGI-based setups was disclosed. Developers attempted to fix this long-standing, but only recently discovered, flaw in a new version on 3 May, before deciding the fix was incomplete and releasing a new set of patches on Tuesday, 8 May.
This is just as well because the PHP-CGI vulnerability has become the target of a series of attacks against sites hosted by DreamHost and others over recent days. Attempts to exploit the bug were witnessed by net honeypots maintained by security researchers at TrustWave SpiderLabs. The assaults were ultimately designed to plant backdoors on vulnerable web servers, as an advisory by TrustWave explains.
The PHP-CGI remote code execution bug was discovered by security researchers, who traced the flaw to changes introduced in the codebase way back in 2004. The Eindbazen crew told PHP developers about the bug, and work was going on behind the scenes to develop a fix. However the wheels fell off this project after discussions surrounding the security hole were accidentally made public, exposing the existence of the flaw to world+dog before a patch was ready.
This, in turn, prompted the decision to rush out updates that failed to close the hole before this week's release of a second set of security updates.
PHP 5.4.3 also addresses a buffer overflow vulnerability in the apache_request_headers, as explained in an advisory here. ®