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

Static analysis result for SHA-256 b5a48fdc202679ff…

MALICIOUS

Office (OOXML) / .DOCX

405.6 KB
MD5: edc3089c5ebfed99009c90d82cb09ecc SHA-1: 63d2a1126677b08aa76ab046b737c43787c07505 SHA-256: b5a48fdc202679ffa0ec4d0078de40db030acff60b44f8e4d4ec190f15165e37
340 Risk Score

Malware Insights

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

The OOXML document contains an altChunk that imports an RTF file (word/Croatia.rtf). This RTF file contains OLE objects, specifically an embedded executable triggered by \objupdate. The presence of RTF_MZ_HEX and RTF_EXCESSIVE_HEX heuristics indicates that a PE executable is embedded within the RTF data. The OOXML_ALTCHUNK_RTF_AUTOUPDATE_PE heuristic confirms that this embedded executable is set to auto-update, indicating a malicious payload delivery mechanism. No scripts were extracted, and the document body was not provided, but the heuristics strongly suggest a malware dropper.

Heuristics 9

  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    (in altChunk RTF word/Croatia.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/Croatia.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.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    (in altChunk RTF word/Croatia.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/Croatia.rtf) RTF contains ~1455KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/Croatia.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/Croatia.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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00003a12.bin
1675c152405de853179580455eb63fe6a2af9eea7cc12f944d2f0e8dba849f86
rtf-objdata-decoded RTF \objdata at offset 0x3A12 740586 bytes
objdata_01_off00178c18.bin
72bd76599c17052cc34443573f8b849d1967d3263c0e0f0118bc6c097634a998
rtf-objdata-decoded RTF \objdata at offset 0x178C18 584266 bytes