MALICIOUS
380
Risk Score
Malware Insights
MITRE ATT&CK
T1566.001 Spearphishing Attachment
T1204.002 Malicious File
T1027 Obfuscated Files or Information
The sample is a DOCX file that leverages OOXML altChunk to import an RTF document. This RTF document contains OLE objects that are activated via \objupdate and exhibit excessive hex data, including a PE header. The critical heuristic OOXML_ALTCHUNK_RTF_AUTOUPDATE_PE indicates that the altChunk RTF auto-updates an embedded executable object, and the CVE-2026-21514 heuristic confirms a Word/OLE security bypass vulnerability is exploited. This suggests the document is designed to deliver and execute a payload.
Heuristics 10
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Composite Moniker in RTF OLE object high RTF_COMPOSITE_MONIKER_RELATED(in altChunk RTF word/Rovide.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/Rovide.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/Rovide.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/Rovide.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/Rovide.rtf) RTF contains ~1660KB 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/Rovide.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
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Embedded OLE object medium RTF_OBJEMB(in altChunk RTF word/Rovide.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.bin60e26aa345f2274a2911aab96c69f1c4b726ebb6fbc2d64fcfa2e1ccd102a5f8 |
rtf-objdata-decoded | RTF \objdata at offset 0xAF73F | 726186 bytes |
objdata_01_off0021d7ef.bin1d48d4a3e65f8a05987e1eda8311ee76b9d4e1777cf26cf570f3238533768635 |
rtf-objdata-decoded | RTF \objdata at offset 0x21D7EF | 585386 bytes |
rtf_svb_00000009.zip2352c9fffd0fd8eba341b4fd80ae0a94a85929bec042e2061b1f17cd52df50f2 |
rtf-svb-package | RTF \svb hex-decoded ZIP at offset 0x9 | 116884 bytes |
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