Bifrost RTF malware analysis — malicious · 45c9d52f2d1aa647

MALICIOUS

RTF

356.6 KB Authoring application: Msftedit 5.41.15.1507

MD5: 793cf224034dae76e2b44c7957e07e18 SHA-1: 7decedfb5bd7502947658d8f846aa08e23eb34f1 SHA-256: 45c9d52f2d1aa647200268fe31bde7b80bbafa83c0c4636c58d76c73b7496fb2

202 Risk Score

Malware Insights

Bifrost · confidence 95%

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1105 Ingress Tool Transfer T1027 Obfuscated Files or Information

The RTF file contains an embedded OLE object which is identified as a PE executable. ClamAV signatures indicate this executable is 'Win.Dropper.Bifrost-9992400-0'. The presence of RTF object data and an embedded PE file strongly suggests a malicious dropper is present. The extracted executable is the primary IOC.

Heuristics 6

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 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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000000f6.bin` `a1630e18c5f5a4b9c2689eb837157064fab798f22d2b5a9c4da5fe0df61dc479`	rtf-objdata-decoded	RTF \objdata at offset 0xF6	177902 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.92, consistent with packed or encrypted content.
`embedded_rtf_000068ff.exe` `f60107b8a8198288d653b7c74577c4728d42f96a7bf8972a6bf9aaf597e089e3`	embedded-pe	RTF hex-encoded MZ at offset 0x68FF	164925 bytes
Detection ClamAV: Win.Dropper.Bifrost-9992400-0 Obfuscation or payload: likely Carved artifact entropy is 7.98, consistent with packed or encrypted content.

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