Malware Insights
The OOXML document contains an altChunk that imports an RTF file (word/Croatia.rtf). This RTF file contains OLE objects, specifically an embedded executable triggered by \objupdate. The presence of RTF_MZ_HEX and RTF_EXCESSIVE_HEX heuristics indicates that a PE executable is embedded within the RTF data. The OOXML_ALTCHUNK_RTF_AUTOUPDATE_PE heuristic confirms that this embedded executable is set to auto-update, indicating a malicious payload delivery mechanism. No scripts were extracted, and the document body was not provided, but the heuristics strongly suggest a malware dropper.
Heuristics 9
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Composite Moniker in RTF OLE object high RTF_COMPOSITE_MONIKER_RELATED(in altChunk RTF word/Croatia.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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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/Croatia.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/Croatia.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/Croatia.rtf) RTF contains ~1455KB 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/Croatia.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
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Embedded OLE object medium RTF_OBJEMB(in altChunk RTF word/Croatia.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://opendope.org/xpaths
- http://opendope.org/conditions
- http://opendope.org/questions
- http://opendope.org/components
- http://opendope.org/SmartArt/DataHierarchy
- http://schemas.openxmlformats.org/wordprocessingml/2006/main
- http://schemas.openxmlformats.org/officeDocument/2006/math
- http://schemas.openxmlformats.org/officeDocument/2006/relationships
- http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing
- http://schemas.openxmlformats.org/drawingml/2006/main
- http://schemas.openxmlformats.org/schemaLibrary/2006/main
- http://schemas.openxmlformats.org/drawingml/2006/chart
- http://schemas.openxmlformats.org/drawingml/2006/chartDrawing
- http://schemas.openxmlformats.org/drawingml/2006/diagram
- http://schemas.openxmlformats.org/drawingml/2006/picture
- http://schemas.openxmlformats.org/drawingml/2006/spreadsheetDrawing
- http://schemas.microsoft.com/office/drawing/2008/diagram
- http://schemas.openxmlformats.org/officeDocument/2006/bibliography
- http://schemas.openxmlformats.org/drawingml/2006/compatibility
- http://schemas.openxmlformats.org/drawingml/2006/lockedCanvas
Extracted artifacts 2
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
objdata_00_off00003a12.bin1675c152405de853179580455eb63fe6a2af9eea7cc12f944d2f0e8dba849f86 |
rtf-objdata-decoded | RTF \objdata at offset 0x3A12 | 740586 bytes |
objdata_01_off00178c18.bin72bd76599c17052cc34443573f8b849d1967d3263c0e0f0118bc6c097634a998 |
rtf-objdata-decoded | RTF \objdata at offset 0x178C18 | 584266 bytes |
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