Malicious RTF — malware analysis report

Static analysis result for SHA-256 fd235ba4df303899…

MALICIOUS

RTF

10.9 KB First seen: 2022-11-17
MD5: 1f4090af8212f58a03b0ec2bd8095c87 SHA-1: c45ab70eede22eb60a7b722358779acee5276c92 SHA-256: fd235ba4df303899107c8eaa0da9eab2380a1da1fc2236033b90123437f42449
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability by embedding an obfuscated Equation Editor object. This technique is commonly used to achieve arbitrary code execution, typically for downloading and executing further malicious content. The specific Equation Editor class 'EqUATioN.3' is a strong indicator of 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_off00001c56.bin
0317457aaff3aecb177b03a2dc6408b3f88432932627edf5098d753cfd9f713c		 rtf-objdata-decoded RTF \objdata at offset 0x1C56 1896 bytes

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