CVE-2015-8994 Detail

Current Description

An issue was discovered in PHP 5.x and 7.x, when the configuration uses apache2handler/mod_php or php-fpm with OpCache enabled. With 5.x after 5.6.28 or 7.x after 7.0.13, the issue is resolved in a non-default configuration with the opcache.validate_permission=1 setting. The vulnerability details are as follows. In PHP SAPIs where PHP interpreters share a common parent process, Zend OpCache creates a shared memory object owned by the common parent during initialization. Child PHP processes inherit the SHM descriptor, using it to cache and retrieve compiled script bytecode ("opcode" in PHP jargon). Cache keys vary depending on configuration, but filename is a central key component, and compiled opcode can generally be run if a script's filename is known or can be guessed. Many common shared-hosting configurations change EUID in child processes to enforce privilege separation among hosted users (for example using mod_ruid2 for the Apache HTTP Server, or php-fpm user settings). In these scenarios, the default Zend OpCache behavior defeats script file permissions by sharing a single SHM cache among all child PHP processes. PHP scripts often contain sensitive information: Think of CMS configurations where reading or running another user's script usually means gaining privileges to the CMS database.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  7.5 HIGH
Vector:  CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H


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Note: NVD Analysts have published a CVSS score for this CVE based on publicly available information at the time of analysis. The CNA has not provided a score within the CVE List.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
http://marc.info/?l=php-internals&m=147876797317925&w=2 Mailing List 
http://marc.info/?l=php-internals&m=147921016724565&w=2 Mailing List 
http://openwall.com/lists/oss-security/2017/02/28/1 Mailing List 
http://seclists.org/oss-sec/2016/q4/343 Mailing List 
http://seclists.org/oss-sec/2017/q1/520 Mailing List 
https://bugs.php.net/bug.php?id=69090 Exploit  Issue Tracking 
https://ma.ttias.be/a-better-way-to-run-php-fpm/ Exploit  Technical Description  Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-264 Permissions, Privileges, and Access Controls cwe source acceptance level NIST  

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Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2015-8994
NVD Published Date:
03/02/2017
NVD Last Modified:
03/16/2017
Source:
MITRE