PHP 'zero-day' hole found

A dangerous vulnerability has been discovered in PHP-CGI which grants attackers remote code execution and the ability to steal source code.

The hole was publicly disclosed reportedly in error to Reddit following a patch issued by PHP Group, but the fix was later discovered by researcher Steffan Esser to have failed.

Researchers from Dutch security firm De Eindbazen discovered the vulnerability during a capture-the-flag event at the Nullcon event last year.

The security emergency release to fix the PHP CGI RCE (that was tested for days...) does not fix anything at all.

— Stefan Esser (@i0n1c) May 3, 2012

A workaround fix on which the failed patches (PHP versions 5.3.12 and 5.4.2) were based was posted to De Eindbbazen's web site which included technical details on the flaw.

Researchers warned that users not follow “homebrew” fixes posted in online comments about the flaw.

The flaw affected classic CGI servers and was centred on a query string that issued a “-s” command argument pushed to PHP. It had existed since 2004, researchers said.

The research firm recommended users use a wrapper binary around the php-cgi binary until a permanent fix is released.

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