Vulnerability identifier: #VU4201

Vulnerability risk: Critical

CVSSv3.1: 9.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2012-1823

CWE-ID: CWE-78

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
PHP
Universal components / Libraries / Scripting languages

Vendor: PHP Group

Description
The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The weakness exists due to error when parsing QUERY_STRING parameters within PHP-CGI-based application (sapi/cgi/cgi_main.c). A remote attacker can send specially crafted HTTP request with query string without the "=" (equals sign) character, inject and execute arbitrary OS commands on vulnerable system with privileges of the web server.

Successful exploitation of the vulnerability results in denial of service or arbitrary code execution on the vulnerable system.

Note: the vulnerability was being actively exploited.

Mitigation
Update to version 5.3.12 or 5.4.2 or later.

Vulnerable software versions

PHP: 5.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.11, 5.4.0 - 5.4.1

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External links
http://bugs.php.net/bug.php?id=61910

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.