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CVE-2012-2311

Published: 4 May 2012

sapi/cgi/cgi_main.c in PHP before 5.3.13 and 5.4.x before 5.4.3, when configured as a CGI script (aka php-cgi), does not properly handle query strings that contain a %3D sequence but no = (equals sign) character, which allows remote attackers to execute arbitrary code by placing command-line options in the query string, related to lack of skipping a certain php_getopt for the 'd' case. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-1823.

From the Ubuntu security team

It was discovered that PHP, when used as a stand alone CGI processor for the Apache Web Server, did not properly parse and filter query strings. This could allow a remote attacker to execute arbitrary code running with the privilege of the web server. Configurations using mod_php5 and FastCGI were not vulnerable.

Notes

AuthorNote
sbeattie
Please see http://www.php.net/archive/2012.php#id2012-05-06-1 for
more details when using configurations other than as described in
/usr/share/doc/php5-cgi/README.Debian.gz.

Mitigation

The php-security.net article has an updated set of mod_rewrite rules that
can mitigate the vulnerability as well:
  RewriteEngine on
  RewriteCond %{QUERY_STRING} ^[^=]*$
  RewriteCond %{QUERY_STRING} %2d|\- [NC]
  RewriteRule .? - [F,L]
Priority

Medium

Status

Package Release Status
php5
Launchpad, Ubuntu, Debian
hardy
Released (5.2.4-2ubuntu5.24)
lucid
Released (5.3.2-1ubuntu4.15)
natty
Released (5.3.5-1ubuntu7.8)
oneiric
Released (5.3.6-13ubuntu3.7)
precise
Released (5.3.10-1ubuntu3.1)
upstream Needs triage