Sambar Server 5.x - Open Proxy / Authentication Bypass

source: https://www.securityfocus.com/bid/10256/info

Sambar improperly validates the IP address of an originating connection and can be used to gain access the administration interface without authorization.

Once the remote attacker has gained access to the administrative interface, further attacks are possible, including privilege escalation and unauthorized system access.

-> GET / HTTP/1.1
Connection: keep-alive
*This is valid web server request. It's granted.

<- Sambar default web page

*Because the connection is keep-alive it's not broken after page is sent.

-> GET http://www.example.com HTTP/1.1

*This is valid proxy requests. This time source IP is not validated, because connection was established before

<- Web page from external site
*Sambar proxies our request.