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

Static analysis result for SHA-256 df656a1c68902fc6…

MALICIOUS

Office (OOXML) / .DOCX

589.4 KB
MD5: 1c6c0bebe1cfb158e4bbbb840342ebc1 SHA-1: 9365aa45f5998aaa399ab98a0153f357fc4628bc SHA-256: df656a1c68902fc6b1b2f7f7385eee044d15320311a9adad0f3a12af4e8d30bf
400 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1027 Obfuscated Files or Information T1140 Deobfuscate/Decode Files or Information T1204.002 Malicious File

The OOXML document utilizes the altChunk mechanism to import an RTF file named 'Guatemala.rtf'. This RTF file contains an OLE object that is activated via \objupdate, and it includes excessive hex data and a PE header, indicating it's an embedded executable. The ClamAV detection 'Rtf.Dropper.Agent-9965975-1' further confirms its malicious nature as a dropper. The primary attack vector is the import and execution of the embedded PE file.

Heuristics 10

  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    (in altChunk RTF word/Guatemala.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/Guatemala.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/Guatemala.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/Guatemala.rtf) RTF contains ~2395KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/Guatemala.rtf) RTF contains 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/Guatemala.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
c9deed99fcf620440e51c3fac9131fcb1e59fdd0ce09a28aeb9ec66c9c94d0bc
rtf-objdata-decoded RTF \objdata at offset 0xE7DA6 745554 bytes
objdata_02_off0025f67c.bin
baa851e508de0c0fe3796025d004df72ceebc7132470d4cc307f31e2abe6c1fc
rtf-objdata-decoded RTF \objdata at offset 0x25F67C 584266 bytes