Malicious Office (OOXML) / .DOCX — malware analysis report

Static analysis result for SHA-256 e3077c9b095fbabf…

MALICIOUS

Office (OOXML) / .DOCX

612.7 KB
MD5: c5ba8e16b8b9049c1acdb656040f8920 SHA-1: 70c1929479a2cdb8fa88a1ad89cc26ce60d7f080 SHA-256: e3077c9b095fbabf72fd5c63f5e2a84371c349a057f1b6daacd529a3b0ca79d6
400 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is a DOCX file that uses the OOXML altChunk mechanism to import an external RTF file ('word/Japan.rtf'). This RTF file contains OLE objects that are automatically updated and activated, as indicated by the RTF_OBJUPDATE and RTF_OBJDATA heuristics. Critical heuristics like RTF_MZ_HEX and OOXML_ALTCHUNK_RTF_AUTOUPDATE_PE confirm that the imported RTF contains and executes a PE (Portable Executable) file. ClamAV detection further identifies it as 'Rtf.Dropper.Agent-9965975-1', suggesting its primary function is to drop and execute a secondary payload.

Heuristics 10

  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    (in altChunk RTF word/Japan.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/Japan.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/Japan.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/Japan.rtf) RTF contains ~2444KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/Japan.rtf) RTF contains 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/Japan.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
25c58b6da32ff90d0415dee2d75cd99af8d3511d7e7789fe6f65bef2967fd0d1
rtf-objdata-decoded RTF \objdata at offset 0x3A12 464881 bytes
objdata_01_off000e7da6.bin
8f44a76f0bbe30739d77f192423281a427e32f66d11b86ecc64357be1fc74b9b
rtf-objdata-decoded RTF \objdata at offset 0xE7DA6 770130 bytes
objdata_02_off0026b67c.bin
baa851e508de0c0fe3796025d004df72ceebc7132470d4cc307f31e2abe6c1fc
rtf-objdata-decoded RTF \objdata at offset 0x26B67C 584266 bytes