BOOSTWRITE

Executive Summary

BoostWrite functions as a loader that leverages DLL search order hijacking to compromise legitimate Windows applications used by the FIN7 group. It serves as a foothold for downloading additional malicious payloads and establishes covert C2 channels, facilitating persistent presence in victim environments.

BOOSTWRITE is a Windows loader designed to be executed through DLL search order hijacking, a technique exploited by the FIN7 group in known supply‑chain attacks such as those documented by FireEye in October 2019. The loader operates by placing a malicious DLL in a directory that precedes the legitimate directory of a target application, causing the victim process to load the attacker’s payload instead of the intended library. Once loaded, BOOSTWRITE typically performs initial reconnaissance on the host system and establishes covert communication channels with command‑and‑control infrastructure. This facilitates further download or execution of additional malware components—often custom backdoors or credential‑stealing utilities—tailored for long‑term persistence and lateral movement within corporate networks. The loader also incorporates evasion tactics such as process name obfuscation and fileless execution where possible. Overall, the impact of BOOSTWRITE is significant: by compromising legitimate applications via DLL hijacking, it grants attackers footholds that bypass many traditional security controls. Attackers can exfiltrate sensitive data, pivot to critical systems, or deploy ransomware modules, all while remaining beneath the radar of basic antivirus and endpoint detection solutions.

Key Capabilities

• DLL search order hijacking
• Loader of additional malware components
• C2 communication for remote control
• Covert persistence via legitimate processes

ATT&CK Techniques

Recommended Actions

• Deploy file integrity monitoring to detect unauthorized DLL placements in critical application directories
• Enable Windows Defender Exploit Guard or similar DLL protection features
• Implement Process Mitigation policies (DLL Search Order Hijack Protection)
• Conduct regular vulnerability assessments of supply‑chain software
• Use network segmentation and strict egress filtering to impede C2 traffic

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