Synopsis
The remote web server is affected by multiple vulnerabilities.
Description
According to its banner, the version of Apache running on the remote host is 2.2.x prior to 2.2.32. It is, therefore, affected by the following vulnerabilities :
- The Apache HTTP Server is affected by a man-in-the-middle vulnerability known as 'httpoxy' due to a failure to properly resolve namespace conflicts in accordance with RFC 3875 section 4.1.18. The HTTP_PROXY environment variable is set based on untrusted user data in the 'Proxy' header of HTTP requests. The HTTP_PROXY environment variable is used by some web client libraries to specify a remote proxy server. An unauthenticated, remote attacker can exploit this, via a crafted 'Proxy' header in an HTTP request, to redirect an application's internal HTTP traffic to an arbitrary proxy server where it may be observed or manipulated.
(CVE-2016-5387)
- A flaw exists due to improper handling of whitespace patterns in user-agent headers. An unauthenticated, remote attacker can exploit this, via a specially crafted user-agent header, to cause the program to incorrectly process sequences of requests, resulting in interpreting responses incorrectly, polluting the cache, or disclosing the content from one request to a second downstream user-agent. (CVE-2016-8743)
- A CRLF injection allowing HTTP response splitting attacks for sites which use mod_userdir (CVE-2016-4975)
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
Solution
Upgrade to Apache version 2.2.32 or later.
Note that the 'httpoxy' vulnerability can be mitigated by applying the workarounds or patches as referenced in the vendor advisory asf-httpoxy-response.txt.