Malicious RTF — malware analysis report

Static analysis result for SHA-256 8bc7a38c063b90b2…

MALICIOUS

RTF

4.2 KB First seen: 2023-01-11
MD5: e60e211fa9c1438f55b88266cec6124b SHA-1: a3e786658ebd3d4c6cc47d4d450ec5fb402b8735 SHA-256: 8bc7a38c063b90b2ae3129b3ba5a2b85bba05e7dc008f5680cd46b9cc1cd041e
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains embedded OLE object data, specifically related to Equation Editor. Heuristics indicate the exploitation of CVE-2017-11882, which is a known vulnerability allowing for arbitrary code execution when the embedded object is activated. The presence of `equAtion.3` as a class name further confirms this exploit vector.

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.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000071.bin
1bb6f48c75c665d0f16278e8ce7495f48eda9ebf07faff38eedab8f5bacc5753		 rtf-objdata-decoded RTF \objdata at offset 0x71 2044 bytes

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