HTTP_PROXY Environment Variable Namespace Collision Vulnerability (httpoxy)
Medium Nessus Plugin ID 92539
SynopsisThe remote web application is affected by a man-in-the-middle vulnerability.
DescriptionThe web application running on the remote web 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.
SolutionApplicable libraries and products should be updated to address this vulnerability. Please consult the library or product vendor for available updates.
If updating the libraries and products is not an option, or if updates are unavailable, filter 'Proxy' request headers on all inbound requests.