Adversaries may check for Internet connectivity on compromised systems. This may be performed during automated discovery and can be accomplished in numerous ways such as using Ping,
tracert, and GET requests to websites.
Adversaries may use the results and responses from these requests to determine if the system is capable of communicating with their C2 servers before attempting to connect to them. The results may also be used to identify routes, redirectors, and proxy servers.
During the SolarWinds Compromise, APT29 used GoldFinder to perform HTTP GET requests to check internet connectivity and identify HTTP proxy servers and other redirectors that an HTTP request travels through.
This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.
Monitor executed commands and arguments that may check for Internet connectivity on compromised systems.
Monitor for executed processes (such as tracert or ping) that may check for Internet connectivity on compromised systems.