Malware Insights
The sample is a DOCX file that leverages an altChunk to import RTF content. This RTF content contains OLE objects and exploits known vulnerabilities, specifically CVE-2017-11882 (Equation Editor) and CVE-2017-8759 (MSXML SAX OLE activation). The presence of RTF_EQUATION_EDITOR, CVE_2017_11882_ACTIVATION_RELATED, and CVE_2017_8759 heuristics strongly indicates exploitation of these vulnerabilities. The RTF_OBJUPDATE and RTF_EXCESSIVE_HEX heuristics further support the malicious nature of the embedded OLE object. The CVE_2026_21514 heuristic suggests an additional exploit related to Word/OLE security bypass. The primary attack vector appears to be exploiting these vulnerabilities to execute arbitrary code, likely to download and run a secondary payload.
Heuristics 10
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CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759(in altChunk RTF word/ctiv.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.
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Equation Editor activation — CVE-2017-11882 related high CVE_2017_11882_ACTIVATION_RELATED(in altChunk RTF word/ctiv.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.
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CVE-2026-21514 — Word/OLE security bypass in RTF high CVE likely CVE_2026_21514(in altChunk RTF word/ctiv.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.
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altChunk imports embedded RTF (RTF injection) critical OOXML_ALTCHUNK_RTFDocument 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.
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Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR(in altChunk RTF word/ctiv.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.
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\objupdate forces OLE activation high RTF_OBJUPDATE(in altChunk RTF word/ctiv.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.
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Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX(in altChunk RTF word/ctiv.rtf) RTF contains ~1000KB of hex-encoded data inside \objdata sections — may hide a payload
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OLE object data medium RTF_OBJDATA(in altChunk RTF word/ctiv.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
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Embedded OLE object medium RTF_OBJEMB(in altChunk RTF word/ctiv.rtf) RTF contains \objemb — embedded OLE object
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Embedded URL info EMBEDDED_URLOne 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.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 3
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
objdata_00_off000af79f.bine78c010be0ab976f39b139ac947555d4aa016cbd406bf364843478a77f4e7127 |
rtf-objdata-decoded | RTF \objdata at offset 0xAF79F | 104958 bytes |
objdata_01_off000ee2f7.bin9eb5935f1e6ca9158ca7617a03e6149dac269a423ccdcf0057f755df707237d9 |
rtf-objdata-decoded | RTF \objdata at offset 0xEE2F7 | 584266 bytes |
rtf_svb_00000009.zip28fc295dafc0bcccd998d6dc34a4e9ae47eb34cb74cb4b892eb6454833467799 |
rtf-svb-package | RTF \svb hex-decoded ZIP at offset 0x9 | 116932 bytes |
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