Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f5d9ae1e85ed2fe6…

MALICIOUS

RTF / .DOC

28.5 KB First seen: 2023-01-17
MD5: dbb709a10a883280c2ea7a0eb3e527ec SHA-1: e20e0fa6f13a4243c4f7b549ff77e086052e6509 SHA-256: f5d9ae1e85ed2fe60f50451241beff053b4d0e5945bbdfc62d2af485cb6ce363
220 Risk Score

Malware Insights

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

The sample is an RTF document that contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The document also includes a lure instructing the user to 'Enable editing' to view its content, which is a common tactic for macro-based malware. The embedded object's ProgID 'EquatIon.3' further confirms the exploitation attempt.

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_off00005aca.bin
a747060b2a6ad7759bba9d7c523aa918d746389ab749df71b3babb7bb99cd89d		 rtf-objdata-decoded RTF \objdata at offset 0x5ACA 1697 bytes

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