Hashing prevention

Perhaps the most common IOC collected by malware analysts, file hashes in MD5, SHA256, and SSDEEP are the fingerprints of files we've previously discussed during static analysis.

While even one bit being changed will alter the entirety of a standard, static cryptographic hash, oftentimes a single hash or small subset of hashes is utilized in any given attack, and being able to quickly blacklist and prevent the execution of these can greatly hinder an attack and buy necessary time to implement better preventative controls, or enable the IR team to find the point of ingress and close it off.

Thankfully, there are several ways we can implement hash-based blocking very quickly and efficaciously across an environment.

Blocking hash execution with Group Policy

Previously in the world of Windows, the primary way to block the execution of files was only via their filename. Within the world of adversarial tools such as Cobalt Strike and Metasploit, however...