Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c8da9dbb52f8297e…

MALICIOUS

RTF / .DOC

28.7 KB First seen: 2022-12-16
MD5: e0f08e6de79794f1ee62088b20ebd51e SHA-1: 2fa3b54e43aca152213c5c6cb87de805486200e4 SHA-256: c8da9dbb52f8297ec83361a3a728c87c5672b06b39fb097ab069303072d1c43b
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 an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The document body includes a lure instructing the user to 'Enable editing' to view the content, a common tactic for macro-based malware. The exploitation of CVE-2017-11882 is directly indicated by multiple high-severity heuristic firings.

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_off00005af1.bin
d4ebf0f7f88338c1dc8bb8e5c9e3264e19fd4d0ec7b13a38d791d96773110bda		 rtf-objdata-decoded RTF \objdata at offset 0x5AF1 1726 bytes

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