MALICIOUS
420
Risk Score
Malware Insights
MITRE ATT&CK
T1187 Exploitation for Client Execution
T1559.002 Component Object Model Hijacking
The sample leverages OOXML altChunk to import an RTF object, which in turn contains OLE objects and PE executable data. The RTF object is designed to exploit CVE-2026-21514, a Word/OLE security bypass, to automatically update and execute the embedded executable. This indicates a downloader or dropper functionality.
Heuristics 11
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Composite Moniker in RTF OLE object high RTF_COMPOSITE_MONIKER_RELATED(in altChunk RTF word/Strea.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.
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CVE-2026-21514 — Word/OLE security bypass in RTF high CVE likely CVE_2026_21514(in altChunk RTF word/Strea.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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PE header (with DOS stub) in hex data critical RTF_MZ_HEX(in altChunk RTF word/Strea.rtf) Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
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altChunk RTF auto-updates embedded executable object critical OOXML_ALTCHUNK_RTF_AUTOUPDATE_PEOOXML 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.
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\objupdate forces OLE activation high RTF_OBJUPDATE(in altChunk RTF word/Strea.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/Strea.rtf) RTF contains ~1903KB of hex-encoded data inside \objdata sections — may hide a payload
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External relationship high OOXML_EXTERNAL_RELExternal target in word/_rels/settings.xml.rels: file:///C:\Users\John\AppData\Roaming\Microsoft\Templates\Student report with photo.dotx
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OLE object data medium RTF_OBJDATA(in altChunk RTF word/Strea.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
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Embedded OLE object medium RTF_OBJEMB(in altChunk RTF word/Strea.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
Extracted artifacts 3
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
objdata_00_off000af73f.bin599b9755c78b27da05850e2eed314e9d824553522420bacdcf4007d375d586c6 |
rtf-objdata-decoded | RTF \objdata at offset 0xAF73F | 847514 bytes |
objdata_01_off00258bcf.bin24ee741dd41bc27803d80f81b66eba686fe8f5d17bd847727dc5d94834bd3188 |
rtf-objdata-decoded | RTF \objdata at offset 0x258BCF | 584826 bytes |
rtf_svb_00000009.zip2352c9fffd0fd8eba341b4fd80ae0a94a85929bec042e2061b1f17cd52df50f2 |
rtf-svb-package | RTF \svb hex-decoded ZIP at offset 0x9 | 116884 bytes |
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