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

Heuristics 13

• CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
  (in altChunk RTF word/Fession.rtf) RTF contains a hex-encoded OLE1 object for Msxml2.SAXXMLReader.6.0 followed by an embedded OLE compound document, and the document requests OLE activation. This matches the RTF staging shape used for CVE-2017-8759 SOAP/WSDL parser code injection.
• Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
  (in altChunk RTF word/Fession.rtf) RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
• Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
  (in altChunk RTF word/Fession.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.
• CVE-2026-21514 — Word/OLE security bypass in RTF high CVE likely CVE_2026_21514
  (in altChunk RTF word/Fession.rtf) RTF contains a hidden \svb hex package with DrsE2oDoc and downRevStg drawing compatibility parts. This matches an observed CVE-2026-21514 exploitation shape that manipulates Word's internal document structure and trust decisions.
• 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.
• Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
  (in altChunk RTF word/Fession.rtf) RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
• PE header (with DOS stub) in hex data critical RTF_MZ_HEX
  (in altChunk RTF word/Fession.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/Fession.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/Fession.rtf) RTF contains ~1693KB of hex-encoded data inside \objdata sections — may hide a payload
• OLE object data medium RTF_OBJDATA
  (in altChunk RTF word/Fession.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
• Embedded OLE object medium RTF_OBJEMB
  (in altChunk RTF word/Fession.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://ocsp.thawte.com0

  • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas
  • http://schemas.microsoft.com/office/drawing/2014/chartex
  • http://schemas.openxmlformats.org/markup-compatibility/2006
  • http://schemas.openxmlformats.org/officeDocument/2006/relationships
  • http://schemas.openxmlformats.org/officeDocument/2006/math
  • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawing
  • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing
  • http://schemas.openxmlformats.org/wordprocessingml/2006/main
  • http://schemas.microsoft.com/office/word/2010/wordml
  • http://schemas.microsoft.com/office/word/2012/wordml
  • http://schemas.microsoft.com/office/word/2015/wordml/symex
  • http://schemas.microsoft.com/office/word/2010/wordprocessingGroup
  • http://schemas.microsoft.com/office/word/2010/wordprocessingInk
  • http://schemas.microsoft.com/office/word/2006/wordml
  • http://schemas.microsoft.com/office/word/2010/wordprocessingShape
  • http://cs-g2-crl.thawte.com/ThawteCSG2.crl0
  • http://crl.thawte.com/ThawtePCA.crl0
  • https://www.globalsign.com/repository/0
  • http://ocsp.globalsign.com/ca/gstsacasha384g40C
  • http://secure.globalsign.com/cacert/gstsacasha384g4.crt0
  • http://crl.globalsign.com/ca/gstsacasha384g4.crl0
  • http://ocsp2.globalsign.com/rootr606
  • http://crl.globalsign.com/root-r6.crl0G

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