NoSnoop is a Windows-based tool that will let users know if their SSL is being subjected to a man-in-the-middle attack.
NoSnoop is a standalone, browser-independent application that will perform SSL/TLS handshakes with a list of 250 popular websites and examine the certificate chains received from each server. It will alert on any unexpected certificates.
NoSnoop will check for obvious cases (such as interception by a local proxy, your employer’s SSL inspection gateways, or a malware infection), as well as more advanced attacks (for instance, if the root cert is valid but issued by an unexpected organization or country).
An entire scan typically takes less than 30 seconds.
This is currently in beta, so “bugs and/or false positives detections should be expected.”