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

Static analysis result for SHA-256 f6051498dc45e053…

MALICIOUS

Office (OOXML) / .DOCX

604.2 KB Created: 2025-10-22 14:54:00 UTC Authoring application: Microsoft Office Word 16.0000
MD5: e76c19433d6782eb4c42f9c6c1f853db SHA-1: d8401dbfc4fc2c32f629f7e8b3d8a7e67aad28bd SHA-256: f6051498dc45e053a9edab00f35873c74ecdb2beb450962e3a4b946c2529a4c2
420 Risk Score

Malware Insights

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

The document leverages OOXML altChunk to import an RTF object, which contains OLE object data and is configured to auto-update and activate. This process is designed to exploit CVE-2026-21514, a Word/OLE security bypass vulnerability, to execute an embedded PE file. The presence of RTF_MZ_HEX and RTF_EXCESSIVE_HEX heuristics further indicates the embedding of executable content within the RTF. The external relationship points to a template file, suggesting a potential delivery vector.

Heuristics 11

  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    (in altChunk RTF word/Coverage.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/Coverage.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.
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    (in altChunk RTF word/Coverage.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/Coverage.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/Coverage.rtf) RTF contains ~1812KB of hex-encoded data inside \objdata sections — may hide a payload
  • External relationship high OOXML_EXTERNAL_REL
    External target in word/_rels/settings.xml.rels: file:///C:\Users\John\AppData\Roaming\Microsoft\Templates\Student report with photo.dotx
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/Coverage.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/Coverage.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://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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0007cb57.bin
7fe5fd7d540779f559f4cc90773da295559e71e8f588557b96957b4c009c78ca
rtf-objdata-decoded RTF \objdata at offset 0x7CB57 906346 bytes
objdata_01_off00242b87.bin
24ee741dd41bc27803d80f81b66eba686fe8f5d17bd847727dc5d94834bd3188
rtf-objdata-decoded RTF \objdata at offset 0x242B87 584826 bytes
rtf_svb_00000009.zip
711c7ae8823597425a382ad0dfe44f4f85af1a5372b30f5acf408d4a8bc6eaaa
rtf-svb-package RTF \svb hex-decoded ZIP at offset 0x9 12859 bytes