Malicious RTF — malware analysis report

Static analysis result for SHA-256 f8cba90a7241060e…

MALICIOUS

RTF

2.00 MB Created: 2018-03-04 14:26:00 First seen: 2019-02-10
MD5: b8cfc7d1a1b2efb4c5afbfd0078ad82c SHA-1: cc00a3b29218c725c2396d9e680244a5d088d7af SHA-256: f8cba90a7241060eaee757d6aed47fa27eb4990a9d38bc4afa9f054dceba4a5f
522 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document that exploits Equation Editor vulnerabilities (CVE-2017-11882 and CVE-2017-8759) to achieve code execution. The presence of OLE objects and excessive hex-encoded data suggests the embedding of a malicious payload. The 'Enable Editing' prompt is a common lure to bypass security measures.

Heuristics 13

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    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.
  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    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.
  • ClamAV: Doc.Dropper.Agent-6529506-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6529506-0
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1923KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 4 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • OlePres presentation stream in RTF OLE object medium RTF_OLEPRES_STREAM
    RTF contains an embedded OLE object with an OlePres presentation stream. OlePres is an OLE presentation marker and is not enough on its own to identify CVE-2025-21298.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • Embedded URL info EMBEDDED_URL
    One 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/2003/wordm In RTF body

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00002b61.bin rtf-objdata-decoded RTF \objdata at offset 0x2B61 961600 bytes
SHA-256: 0ddc9a58cada4dbbf70a2a16e6bdd873daab8f55d97ce81359d588d5cab3ec90
objdata_01_off001f314c.bin rtf-objdata-decoded RTF \objdata at offset 0x1F314C 4183 bytes
SHA-256: 3382db8f6b736b12a349df724ee213f8b536038f5c7beb126a29c161b5ef93e5
objdata_02_off001f53fa.bin rtf-objdata-decoded RTF \objdata at offset 0x1F53FA 3826 bytes
SHA-256: c4611fd774a89e42093812e4b8d630b0210a476184df69bc6ffbe2418128f165
objdata_03_off001fe520.bin rtf-objdata-decoded RTF \objdata at offset 0x1FE520 3546 bytes
SHA-256: 6e2aea7ea2cc078526bd52a97cd3e0f071a0d34e368f94f41b87a877119743ce

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