MalwareApr 28, 2026
Detection Insight: Suspicious .accdr Dropper Activity (Possible Bitter Tradecraft) A recent our...
Microsoft Access Runtime .accdr files detected as stealthy droppers with minimal AV coverage.
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Summary
Security researchers identified a cluster of malicious Microsoft Access Runtime (.accdr) files functioning as droppers, potentially linked to Bitter threat actor tradecraft. The files exhibited extremely low antivirus detection rates (0/62), suggesting sophisticated evasion techniques. This indicates an active campaign leveraging legitimate Office file formats for payload delivery.
Indicators of Compromise
- malware — .accdr dropper
- mitre_attack — T1566.001
- mitre_attack — T1140
Entities
Bitter (threat_actor)Microsoft Access Runtime (product).accdr file format (technology)