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

Static analysis result for SHA-256 838c41957d93c230…

MALICIOUS

Office (OOXML) / .DOCX

584.9 KB Created: 2021-04-18 19:39:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2026-01-26
MD5: 191fa8508f8dacda501cf137770bf71b SHA-1: 6f738294476e7f5c6b1ecf1d910b51bf58842337 SHA-256: 838c41957d93c2301e7073644d7096724a839e5ee2b84311ebf99dd5b0aafb25
542 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

This OOXML document leverages altChunk to import an RTF file that exploits multiple Microsoft Office vulnerabilities, including CVE-2017-11882 and CVE-2017-8759, to execute embedded code. The RTF object itself contains a PE header and is designed to auto-update and execute, likely serving as a dropper for a secondary payload. The presence of multiple critical RTF-related heuristics and CVE exploits strongly indicates a malicious document designed for initial compromise.

Heuristics 13

  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    (in altChunk RTF word/Harry.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/Harry.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/Harry.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/Harry.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/Harry.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/Harry.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/Harry.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/Harry.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/Harry.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/Harry.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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000af73f.bin
0fd1c76068834c4c2939fa64557214bb7b406160938a2e74a9ac55f5c0d8fc7e
rtf-objdata-decoded RTF \objdata at offset 0xAF73F 742570 bytes
objdata_01_off002257ef.bin
d841fb09458f28707fa3b061de849cdb7c0817ab5e9759696e1890dc6eea4516
rtf-objdata-decoded RTF \objdata at offset 0x2257EF 584266 bytes
rtf_svb_00000009.zip
2352c9fffd0fd8eba341b4fd80ae0a94a85929bec042e2061b1f17cd52df50f2
rtf-svb-package RTF \svb hex-decoded ZIP at offset 0x9 116884 bytes