The concept of “packing” or “crypting” a malicious program is widely popular among threat actors looking to bypass or defeat analysis by static and dynamic analysis tools. Evasion of classification and detection is an arms race in which new techniques are traded and used in the wild. For example, we observe many crypting services being offered in underground forums by actors who claim to make any malware “FUD” or “Fully Undetectable” by anti-virus technologies, sandboxes and other endpoint solutions. We also see an increased effort to model normal user activity and baseline it as an effective countermeasure to fingerprint malware analysis environments.
The Delphi programming language can be an easy way to write applications and programs that leverage Windows API functions. In fact, some actors deliberately include the default libraries as a diversion to hamper static analysis and make the application “look legit” during dynamic analysis.
We have observed many spam campaigns with different themes that drop payloads packed using this packer.