Rtf.Dropper.Agent-9965975-1 — Office (OOXML) / .DOCX malware analysis

Static analysis result for SHA-256 839e29ffd07585a4…

MALICIOUS

Office (OOXML) / .DOCX

420.4 KB
MD5: c52512f228c00969d89940d3d2ecc072 SHA-1: 6cc145b1bb2b726dce285ddd7b348b6756a9803f SHA-256: 839e29ffd07585a45829c06d887fd9ee74240fe6bbf768733fad99c21b5e4d8a
400 Risk Score

Malware Insights

Rtf.Dropper.Agent-9965975-1 · confidence 95%

MITRE ATT&CK
T1559.001 Component Object Model Hijacking T1137.003 DLL Search Order Hijacking T1059.001 PowerShell

The OOXML document utilizes an altChunk to import an external RTF file. This RTF file contains OLE objects, specifically an embedded executable triggered by an \objupdate directive. The presence of RTF_MZ_HEX and RTF_ALTCHUNK_RTF_AUTOUPDATE_PE heuristics confirms that an executable is embedded and designed to auto-update. ClamAV detection further supports this, identifying the sample as Rtf.Dropper.Agent-9965975-1, indicating a dropper functionality.

Heuristics 10

  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    (in altChunk RTF word/Burundi.rtf) RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • altChunk imports embedded RTF (RTF injection) critical OOXML_ALTCHUNK_RTF
    Document inlines an embedded RTF via an aFChunk relationship and a <w:altChunk> body element. This is the canonical RTF-injection wrapper used to smuggle RTF exploits (Equation Editor / URL Moniker / objdata) past DOCX-only scanners. Word opens the wrapper and executes the RTF inline. Recursing into the RTF for the exact exploit primitive.
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    (in altChunk RTF word/Burundi.rtf) Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • altChunk RTF auto-updates embedded executable object critical OOXML_ALTCHUNK_RTF_AUTOUPDATE_PE
    OOXML document imports an embedded RTF through altChunk; the RTF contains OLE object data, forces object update, and carries a hex-encoded PE payload. This is a stronger compound exploit-loader shape than a generic altChunk RTF wrapper, but it is not tied to a single CVE unless the nested RTF object primitive also matches one.
  • ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    (in altChunk RTF word/Burundi.rtf) RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    (in altChunk RTF word/Burundi.rtf) RTF contains ~1904KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/Burundi.rtf) RTF contains 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/Burundi.rtf) RTF contains \objemb — embedded OLE object
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://opendope.org/xpaths
    • http://opendope.org/conditions
    • http://opendope.org/questions
    • http://opendope.org/components
    • http://opendope.org/SmartArt/DataHierarchy
    • http://schemas.openxmlformats.org/wordprocessingml/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/math
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing
    • http://schemas.openxmlformats.org/drawingml/2006/main
    • http://schemas.openxmlformats.org/schemaLibrary/2006/main
    • http://schemas.openxmlformats.org/drawingml/2006/chart
    • http://schemas.openxmlformats.org/drawingml/2006/chartDrawing
    • http://schemas.openxmlformats.org/drawingml/2006/diagram
    • http://schemas.openxmlformats.org/drawingml/2006/picture
    • http://schemas.openxmlformats.org/drawingml/2006/spreadsheetDrawing
    • http://schemas.microsoft.com/office/drawing/2008/diagram
    • http://schemas.openxmlformats.org/officeDocument/2006/bibliography
    • http://schemas.openxmlformats.org/drawingml/2006/compatibility
    • http://schemas.openxmlformats.org/drawingml/2006/lockedCanvas

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00003a12.bin
28d4d6f5ed1af74ac140d6d6ed0c34bba6a3fd60f608cee2cd2e0f648cc86802
rtf-objdata-decoded RTF \objdata at offset 0x3A12 483038 bytes
objdata_01_off000ff6e1.bin
852c953c008d36b87365f68de3ab7ea8e955b0edfbd0c9bb9ed9386bedf0a28e
rtf-objdata-decoded RTF \objdata at offset 0xFF6E1 500306 bytes
objdata_02_off001ff3b7.bin
359f1c8a7119d8f52bd4128ee1ec29c1776e538742ee42f6bc006ca277125b09
rtf-objdata-decoded RTF \objdata at offset 0x1FF3B7 534490 bytes