Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 85041e5cc4fccbad…

MALICIOUS

RTF / .DOC

18.6 KB First seen: 2022-10-05
MD5: 6f7f86e4a1ab983119809937a372e6e1 SHA-1: e35cb2dff3370f3c2b470a05e32e1d54898f22cf SHA-256: 85041e5cc4fccbadc33929ce2059f1f03566601e67f5aff9b938b5f6ae20d605
220 Risk Score

Malware Insights

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

The sample is an RTF document containing a malicious OLE object that exploits CVE-2017-11882 through the Equation Editor. The document body contains a lure instructing the user to 'Enable editing', a common tactic for macro-based malware. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this known vulnerability.

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_off00001d7f.bin
26deb3372dfc8303aaa2461b0d1db86893fd7be48438c57bcb80032dab3c93c1		 rtf-objdata-decoded RTF \objdata at offset 0x1D7F 1725 bytes

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