Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 3199af8e3fda6f94…

MALICIOUS

RTF / .DOC

28.2 KB First seen: 2022-11-22
MD5: 63ebb52245eb047f36401d83199e1c02 SHA-1: ac2c4f21ec62ea7e21e291bd94cec0a2411c1957 SHA-256: 3199af8e3fda6f94e2ae6ccee6973b2ba56587f28f5fffb4f324a93f29acfbd1
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic T1059.003 Windows Command Shell

The file is an RTF document containing an embedded OLE object that exploits CVE-2017-11882 via the Equation Editor. The document body contains a lure instructing the user to 'Enable editing' to view the content, which is a common technique to bypass macro security settings and trigger the exploit. No scripts were extracted, but the presence of the Equation Editor exploit indicates a likely attempt to download and execute a second-stage payload.

Heuristics 6

  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000530d.bin
25c23413a267365b244a98591be38fbcfd7f9da7ce993c61b2c0f85c7d784129		 rtf-objdata-decoded RTF \objdata at offset 0x530D 1656 bytes

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