Win.Malware.Bifrose-9834621-0 RTF malware analysis — malicious · 667a50dd6948cfae

MALICIOUS

RTF

1.53 MB Authoring application: Msftedit 5.41.15.1515

MD5: 375bbef0e6f535251c6f11f82a083684 SHA-1: 6097938a08faaed281ea56934b0c0390375dbc41 SHA-256: 667a50dd6948cfaed43228c567eddca6299e66ea3dac97709b959f17c97e585e

302 Risk Score

Malware Insights

Win.Malware.Bifrose-9834621-0 · confidence 95%

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The RTF file contains a high amount of hex-encoded data within an OLE object, which is flagged as suspicious. ClamAV detections indicate the presence of Win.Malware.Bifrose-9834621-0, likely embedded within the OLE object. The document body text 'Clicke para abrir' suggests a lure to interact with the embedded malicious content.

Heuristics 8

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.Malware.Bifrose-9834621-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Malware.Bifrose-9834621-0
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
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1597KB of hex-encoded data inside \objdata sections — may hide a payload
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.

Filename	Kind	Source	Size
`objdata_00_off000000d2.bin` `8d30b1ecb1c0b194fea1e611e28b82798619ae798fc81c7f02dbe63cb89c0ec1`	rtf-objdata-decoded	RTF \objdata at offset 0xD2	778599 bytes
Detection ClamAV: Win.Malware.Bifrose-9834621-0 Obfuscation or payload: likely Carved artifact entropy is 7.94, consistent with packed or encrypted content.

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