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

Static analysis result for SHA-256 41270db8f7f015f3…

MALICIOUS

Office (OOXML) / .DOCX

576.5 KB Created: 2021-04-18 19:39:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2026-03-24
MD5: cc40a433a350d2dd3247c4ca9b36cd45 SHA-1: 2909a85f4b32b1ecd4a6fb74ac048d516be84184 SHA-256: 41270db8f7f015f3c6d6c4972c237be3366237daf9bd431a60cb024d1eb99033
382 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is a Microsoft Office document that leverages an embedded RTF object via altChunk. This RTF object contains exploits for CVE-2017-11882 (Equation Editor vulnerability) and CVE-2017-8759 (MSXML SAX OLE activation), and CVE-2026-21514. These vulnerabilities allow for the execution of arbitrary code, likely to download and run a second-stage payload. The presence of these specific CVEs strongly indicates exploitation for client execution.

Heuristics 10

  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    (in altChunk RTF word/anage.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/anage.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.
  • CVE-2026-21514 — Word/OLE security bypass in RTF high CVE likely CVE_2026_21514
    (in altChunk RTF word/anage.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/anage.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.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    (in altChunk RTF word/anage.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/anage.rtf) RTF contains ~1001KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/anage.rtf) RTF contains 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/anage.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
    • http://schemas.openxmlformats.org/drawingml/2006/main
    • http://schemas.microsoft.com/office/2006/metadata/properties
    • http://www.w3.org/2001/XMLSchema-instance
    • http://schemas.microsoft.com/office/infopath/2007/PartnerControls
    • http://schemas.openxmlformats.org/officeDocument/2006/customXml
    • http://schemas.microsoft.com/office/2006/metadata/contentType
    • http://schemas.microsoft.com/office/2006/metadata/properties/metaAttributes
    • http://www.w3.org/2001/XMLSchema
    • http://schemas.microsoft.com/office/2006/documentManagement/types
    • http://schemas.openxmlformats.org/package/2006/metadata/core-properties
    • http://purl.org/dc/elements/1.1/
    • http://purl.org/dc/terms/
    • http://schemas.microsoft.com/internal/obd
    • http://dublincore.org/schemas/xmls/qdc/2003/04/02/dc.xsd
    • http://dublincore.org/schemas/xmls/qdc/2003/04/02/dcterms.xsd
    • http://schemas.microsoft.com/sharepoint/v3/contenttype/forms
    • http://schemas.openxmlformats.org/officeDocument/2006/cus�

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000af79f.bin
c42556915fd25bbf48876f4ba43c6d5c7fac0e02fb888246dd314c29a5edffa4
rtf-objdata-decoded RTF \objdata at offset 0xAF79F 94040 bytes
objdata_01_off000e85cc.bin
886b62884d874ef7cbf8fdf3517674d4b6a37e0fc7ff8f44f0c0cd9c5a19b566
rtf-objdata-decoded RTF \objdata at offset 0xE85CC 583146 bytes
objdata_02_off00383d57.bin
47339b925079f7f97966cf6e9e64b7423e6159d33d24aa960f9068e8596e9bd4
rtf-objdata-decoded RTF \objdata at offset 0x383D57 32814 bytes
rtf_svb_00000009.zip
28fc295dafc0bcccd998d6dc34a4e9ae47eb34cb74cb4b892eb6454833467799
rtf-svb-package RTF \svb hex-decoded ZIP at offset 0x9 116932 bytes