Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 95fdcf7ec1c649ab…

MALICIOUS

RTF / .DOC

3.4 KB First seen: 2022-10-10
MD5: d64577ca1c0b9c373e316689846557a7 SHA-1: e7cd50dae79190d183fb196273c74c4188cef561 SHA-256: 95fdcf7ec1c649ab09ef86450257e45e186d9da1f050aeea32cee2fad14e0c2b
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 object is designed to be automatically activated upon opening the document, leading to arbitrary code execution. No specific malware family was identified, but the exploit is a common initial access 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.
  • 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_off00000075.bin
e3900f34daa7a3f4ab0d3fe6505abec5597cede97df96954fa4d603f290668be		 rtf-objdata-decoded RTF \objdata at offset 0x75 1635 bytes

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