Malicious RTF — malware analysis report

Static analysis result for SHA-256 c7fdabfe771881ec…

MALICIOUS

RTF

13.4 KB First seen: 2022-04-13
MD5: 8272f05ddcc8e3007bdaf4063d6eca3d SHA-1: fe6c719a10676c695af30b24d75292753c40619c SHA-256: c7fdabfe771881eca37c0f449960b4a532214746229314ad03a9befa920828ca
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1559.001 Component Object Model Hijacking

The RTF file contains embedded OLE object data, specifically related to Equation Editor. Heuristics indicate a critical firing for RTF_EQUATION_EDITOR and high firings for CVE_2017_11882_ACTIVATION_RELATED and RTF_OBJUPDATE, strongly suggesting exploitation of the CVE-2017-11882 vulnerability. This vulnerability allows for arbitrary code execution when the embedded object is activated.

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 2 \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_off00001ad0.bin
8143a57eb45be69c8922a90ac44e9af3d76ca5992e7db8f497d2c61e2be8f739		 rtf-objdata-decoded RTF \objdata at offset 0x1AD0 1854 bytes

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