Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 8f88a9255bdbb3a5…

MALICIOUS

RTF / .DOC

24.3 KB First seen: 2022-11-08
MD5: 01ec9946188c5226f78471deeb46ec9f SHA-1: 4bd288c4aa8ae97ab36c593e58f9680ffa3a1151 SHA-256: 8f88a9255bdbb3a54238e0716c6d5b23591b5aad540c4fb72159b1cae67845c7
220 Risk Score

Malware Insights

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

The file is an RTF document that contains an embedded OLE object, specifically related to Equation Editor. Heuristics indicate that this object is designed to exploit CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The document also contains a lure instructing the user to 'Enable editing', a common tactic to bypass security measures and trigger the 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.
  • 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_off00004bef.bin
a77b51057a4b254033fcaf29d5e1523ceba842cdaaa5c8887441aeff4b468c5d		 rtf-objdata-decoded RTF \objdata at offset 0x4BEF 1520 bytes

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