Win.Trojan.Buzus-41 — RTF / .DOC malware analysis

Static analysis result for SHA-256 cc3fb2503a7d2b33…

MALICIOUS

RTF / .DOC

73.0 KB Authoring application: Msftedit 5.41.15.1515
MD5: 705a0cbecf6ca291b8e2efe173a87fcf SHA-1: 8453f7a30c837f02f0be63db9cc05d7f133b8eb8 SHA-256: cc3fb2503a7d2b3371d5d6d85dc364845979e5f3cdd0b46b208fce0af05a9d09
262 Risk Score

Malware Insights

Win.Trojan.Buzus-41 · confidence 95%

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF file contains embedded OLE object data, specifically a package object class with a PE header in hex data. ClamAV signatures identify this as Win.Trojan.Buzus-41. The presence of the PE header within the OLE object strongly suggests that this document is intended to deliver a secondary executable payload. The extracted artifact, objdata_00_off000000d1.bin, is also flagged as suspicious by static triage.

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.Trojan.Buzus-41 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Trojan.Buzus-41
  • 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
8396e75fd76389594c73dc84a27c5bb303036e759459a3beffe38cafb6f3ab8a
rtf-objdata-decoded RTF \objdata at offset 0xD1 33049 bytes
Detection
ClamAV: Win.Trojan.Buzus-41
Obfuscation or payload: likely
Carved artifact entropy is 7.47, consistent with packed or encrypted content.