Albert Astals Cid reports:
Using a malicious PAC file, and then using exfiltration methods in the PAC
function FindProxyForURL() enables the attacker to expose full https URLs.
This is a security issue since https URLs may contain sensitive
information in the URL authentication part (user:password@host), and in the
path and the query (e.g. access tokens).
This attack can be carried out remotely (over the LAN) since proxy settings
allow "Detect Proxy Configuration Automatically".
This setting uses WPAD to retrieve the PAC file, and an attacker who has access
to the victim's LAN can interfere with the WPAD protocols (DHCP/DNS+HTTP)
and inject his/her own malicious PAC instead of the legitimate one.
With Rapid7 live dashboards, I have a clear view of all the assets on my network, which ones can be exploited, and what I need to do in order to reduce the risk in my environment in real-time. No other tool gives us that kind of value and insight.
– Scott Cheney, Manager of Information Security, Sierra View Medical Center