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

Static analysis result for SHA-256 8b38648319fed301…

MALICIOUS

Office (OOXML) / .DOCX

187.1 KB Created: 2020-01-30 08:31:00 UTC Authoring application: Microsoft Office Word 16.0000
MD5: 791589d8021f4593141ccc9139803103 SHA-1: a5fd4083779634bad9d270f742f83fb0f5b54b28 SHA-256: 8b38648319fed30176a688858aa230f604d8559309cb59f9120d0e21593e5fdd
300 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File Execution: User Execution T1059.001 PowerShell

The sample is a DOCX file that leverages RTF injection via altChunk to import and exploit vulnerabilities in the Equation Editor (CVE-2017-8759) and an OLE object update mechanism (CVE-2026-21514). This process likely leads to the execution of a second-stage payload. The embedded RTF content contains OLE objects and triggers an objupdate, indicating an attempt to activate and run embedded code. No specific family could be identified, but the exploitation chain is clear.

Heuristics 8

  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    (in altChunk RTF word/chnol.xml) 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.
  • CVE-2026-21514 — Word/OLE security bypass in RTF high CVE likely CVE_2026_21514
    (in altChunk RTF word/chnol.xml) 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/chnol.xml) 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.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    (in altChunk RTF word/chnol.xml) RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/chnol.xml) RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/chnol.xml) 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_off000a967c.bin
45f3957351e87779f98b92d300ea22f9b8f51140e7ca5b1485117da1537539d6		 rtf-objdata-decoded RTF \objdata at offset 0xA967C 66264 bytes
objdata_01_off000d4ba9.bin
a8bedb268c18ee8a8e186a97b2899d1021a6fb8f1ac10e4fb2bf53c5e6442782		 rtf-objdata-decoded RTF \objdata at offset 0xD4BA9 694188 bytes
rtf_svb_00000009.zip
28fc295dafc0bcccd998d6dc34a4e9ae47eb34cb74cb4b892eb6454833467799		 rtf-svb-package RTF \svb hex-decoded ZIP at offset 0x9 116932 bytes

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