Win.Dropper.Bifrose-6983135-0 — RTF malware analysis

Static analysis result for SHA-256 675dc1d3ead1de28…

MALICIOUS

RTF

322.3 KB Authoring application: Msftedit 5.41.15.1515
MD5: 3c008eff14bb80a126004d21476f1b4c SHA-1: 1fece3ab9a64fa1cf91b0d0fde707df568a8babb SHA-256: 675dc1d3ead1de283b7556f0c2b2df163293c6a24f4fb972869a091e86c24bb3
262 Risk Score

Malware Insights

Win.Dropper.Bifrose-6983135-0 · confidence 95%

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The RTF file contains an embedded OLE object which, when decoded, reveals a PE executable. ClamAV signatures identify this as Win.Dropper.Bifrose-6983135-0. The presence of the PE header within the RTF's hex data strongly suggests the file is designed to deliver a secondary payload.

Heuristics 7

  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • ClamAV: Win.Dropper.Bifrose-6983135-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Dropper.Bifrose-6983135-0
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • Package object class high RTF_OBJCLASS_PACKAGE
    OLE Package object — can wrap arbitrary files
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000d1.bin
12f62964f04aeb3c98bdd4aa0c61ab3f3d92addefbb8633726e10e5d1c1411f0		 rtf-objdata-decoded RTF \objdata at offset 0xD1 157069 bytes
Detection
ClamAV: Win.Dropper.Bifrose-6983135-0
Obfuscation or payload: likely
Carved artifact entropy is 7.64, consistent with packed or encrypted content.

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