MALICIOUS
542
Risk Score
Malware Insights
MITRE ATT&CK
T1566.001 Spearphishing Attachment
T1203 Exploitation for Client Execution
This document leverages the CVE-2017-11882 vulnerability in the Equation Editor to embed and execute a malicious RTF object. This object, in turn, contains a PE executable and exploits CVE-2017-8759 for OLE activation, leading to the execution of a secondary payload. The presence of altChunk RTF with auto-updating executable objects strongly indicates a malicious intent to deliver an exploit.
Heuristics 12
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CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882(in altChunk RTF word/afchunk.rtf) Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
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CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759(in altChunk RTF word/afchunk.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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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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Equation Editor CLSID critical RTF_EQUATION_EDITOR(in altChunk RTF word/afchunk.rtf) Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
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PE header (with DOS stub) in hex data critical RTF_MZ_HEX(in altChunk RTF word/afchunk.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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ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTIONClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
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\objupdate forces OLE activation high RTF_OBJUPDATE(in altChunk RTF word/afchunk.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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Package object class high RTF_OBJCLASS_PACKAGE(in altChunk RTF word/afchunk.rtf) OLE Package object — can wrap arbitrary files
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OLE object data medium RTF_OBJDATA(in altChunk RTF word/afchunk.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
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Embedded OLE object medium RTF_OBJEMB(in altChunk RTF word/afchunk.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.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/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 2
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
objdata_00_off000186f0.bin5eda582369843f39739a140ee2d9609d0a067bbd6b9488b60cc845462320fffa |
rtf-objdata-decoded | RTF \objdata at offset 0x186F0 | 135402 bytes |
objdata_01_off0005abee.bin779bb6a1471b4d72c1c6ced5c694c90ab7c774aeb456cc17604065d28839a0e6 |
rtf-objdata-decoded | RTF \objdata at offset 0x5ABEE | 3546 bytes |
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