Curl Web Request with Custom User-Agent
This rule detects the execution of 'curl.exe' when it is used with the '-H' flag to specify a custom 'User-Agent' string. This behavior can be indicative of an attacker attempting to download or exfiltrate data to a domain that requires a specific User-Agent for access, potentially to bypass security controls or blend in with legitimate traffic. The rule specifically looks for the 'curl.exe' image or original filename and the presence of '-H' followed by 'User-Agent:' in the command line.
Sigma
