Remote code execution in PHP

1) Use-after-free error

EUVDB-ID: #VU3611

Risk: High

CVSSv4.0: 8.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Amber]

CVE-ID: CVE-2016-5771

CWE-ID: CWE-416 - Use After Free

Exploit availability: Yes

Description

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

The vulnerability exists due to use-after-free in GC algorithm and unserialize. A remote attacker can create a specially crafted zval object and exploit the PHP process by taking over the EIP/RIP.

Successful exploitation of this vulnerability results in complete control over the vulnerable web application and execute arbitrary PHP code on the target system.

Mitigation

Update to version 5.6.23.

Vulnerable software versions

PHP: 5.5.36 - 5.6.22

CPE2.3

• cpe:2.3:a:php_group:php:5.5.36:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.5.37:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.0:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.1:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.2:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.3:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.4:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.5:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.6:*:*:*:*:*:*:*
• cpe:2.3:a:php_group:php:5.6.7:*:*:*:*:*:*:*

External links

https://bugs.php.net/bug.php?id=72433

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?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.