CGI Web Server Vulnerability

Number: AV16-116
Date: 18 July 2016

Purpose

The purpose of this advisory is to bring attention to multiple security advisories released concerning various web servers running Common Gateway GatewayAn intermediate system that is the interface between two computer networks. A gateway can be a server, firewall, router, or other device that enables data to flow through a network. Interface InterfaceA boundary across which two systems communicate. An interface might be a hardware connector used to link to other devices, or it might be a convention used to allow communication between two software systems. (CGI).

Assessment

CCIRC is aware of multiple vulnerabilities affecting web server hosts running CGI (or allowing the execution of CGI scripts).  Exploitation of these vulnerabilities may allow an attacker to conduct man-in-the-middle (MITM) attacks and/or create denial of service conditions.

These vulnerabilities may be exploitable on any web server allowing execution of CGI and/or CGI-like scripts, with permission to use the variable “HTTP_PROXY”.

CVE References: CVE-2016-5385, CVE-2016-5386, CVE-2016-5387, CVE-2016-5388, CVE-2016-1000109, CVE-2016-1000110

Suggested Action

CCIRC recommends that system administrators identify their affected assets and potential interdependencies with their organization’s critical services, and follow their patch management process accordingly or consider applying the workarounds.

References:

CERT/CC Vulnerability VulnerabilityA flaw or weakness in the design or implementation of an information system or its environment that could be exploited to adversely affect an organization's assets or operations. Note VU#797896 - CGI web servers assign Proxy header values from client requests to internal HTTP_PROXY environment variables:
http://www.kb.cert.org/vuls/id/797896

Security Researcher Website – httpoxy:

https://httpoxy.org