Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 d036c64b87ec37b7…

MALICIOUS

RTF / .DOC

33.0 KB First seen: 2023-02-14
MD5: 618a56c63ea0e7783a5202186ab81e84 SHA-1: d087bff8d2555f942db4568b88802a736fd5f3a6 SHA-256: d036c64b87ec37b71e6885dc260f37109609d4e2bf36d153fe149274c7a5cc91
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document containing an embedded OLE object that exploits CVE-2017-11882 via the Equation Editor. The document also contains a lure instructing the user to 'Enable editing', a common tactic for macro-based malware. The embedded object's class name 'eqUAtiON.3' is a strong indicator of this specific exploit.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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_off0000483e.bin
a6007d26bcf36c05325381b29e2f5b81f9aa9960524297fb720ead96ef720a08		 rtf-objdata-decoded RTF \objdata at offset 0x483E 1294 bytes

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