eParakstītājs 3.0 for Windows – remote code execution via unauthenticated auto-update

Summary

eParakstītājs 3.0 for Windows before version 1.10.0 retrieves and executes its automatic updates over a channel that is not authenticated or integrity-protected. On each launch the application fetches an update descriptor (XML) over TLS but accepts any TLS certificate (a permissive TrustManager and a HostnameVerifier that always returns true), does not verify any digital signature on the update descriptor, and does not verify the Authenticode signature or a checksum of the downloaded installer before running it. A man-in-the-middle attacker able to redirect www.eparaksts.lv can serve a crafted update descriptor pointing to an attacker-controlled executable, which the client downloads and executes, resulting in arbitrary code execution on the victim host.