ASTROLOCKER Ransomware: Technical Analysis and Defense Strategies

The Ransom.Win64.ASTROLOCKER.THCBDBA ransomware represents a moderate-risk threat with high damage potential, primarily targeting Windows environments. First documented by Trend Micro in March 2021, this malware typically arrives as a secondary payload or through drive-by downloads. Security teams should note its self-deleting behavior and selective file encryption capabilities despite its currently limited distribution.

Technical Analysis of Infection Vectors

ASTROLOCKER employs two primary infection methods: as a secondary payload from established malware infections or through user-initiated downloads from compromised websites. The ransomware exhibits sophisticated behaviors including virtual environment checks and automated cleanup after execution. Unlike many ransomware variants, it maintains an exclusion list for specific file extensions during encryption.

The execution flow follows a predictable pattern:

# Pseudocode of ASTROLOCKER's execution flow
def main():
    drop_payload()          # Typically from parent process or download
    check_virtual_env()     # Potential VM/sandbox evasion
    encrypt_files()         # With extension exclusion list
    drop_ransom_note()      # Communication with victims
    self_delete()           # Cleanup after execution

Key Indicators of Compromise

Security teams should monitor for these critical indicators:

Type	Value
SHA-256	2c44444d207a78da7477ae1af195d4265134e895bebb476f7b2c003f1467a033
SHA-256	3dd01b5803b349892e0172c59090a201c819b7a67af859e64b5f4f17fd7ebf91
TOR URLs	w6ilafwwrgtrmilorzqex6pgpvfsa667fydca2wpoluj6sajka225byd.onion
	accdknc4nmu4t5hclb6q6kjm2u7u5xdzjnewut2up2rlcfqe5lootlqd.onion

Defensive Recommendations

For security operations teams, we recommend implementing these protective measures:

Prevention: Block known IOCs at network boundaries and restrict execution from temporary directories
Detection: Monitor for processes that delete themselves after execution and mass file extension changes
Recovery: Maintain offline backups with versioning and test restoration procedures quarterly

For threat hunting teams, this sample Splunk query can help identify potential infections:

index=windows EventCode=1 
| search (ParentImage="*\\mshta.exe" OR ParentImage="*\\powershell.exe") 
AND Image="*\\temp\\*" 
| table _time ComputerName User ParentImage Image CommandLine

Risk Assessment and Mitigation

The malware presents an interesting risk profile with high damage potential but limited current distribution. Its technical capabilities align with modern ransomware threats, particularly in its self-deleting behavior and targeted encryption. Organizations should incorporate the provided IOCs into monitoring systems and review similar ransomware families for overlapping tactics.

For comprehensive protection, security teams should implement layered defenses including: