Malicious RTF — malware analysis report

Static analysis result for SHA-256 90e73df4afa607e8…

MALICIOUS

RTF

4.1 KB First seen: 2022-12-06
MD5: c746fc38543961ccceb2d8479563eb24 SHA-1: bdcd20367cf10fba4e469fd7686f5954bf059bb0 SHA-256: 90e73df4afa607e8067725397493c2781c69b1c2afa6e155c262ee90cb6e3a79
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for the execution of arbitrary code upon activation, likely to download and run a secondary payload. The presence of `eQuatiOn.3` as the ProgID strongly indicates this exploit.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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.
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000006f.bin
1535152a26b4cbc16853aa68d1617b1cf60c6410780776457360c97da8f31489		 rtf-objdata-decoded RTF \objdata at offset 0x6F 2011 bytes

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