Malicious RTF — malware analysis report

Static analysis result for SHA-256 6841bbfdc2ef1768…

MALICIOUS

RTF

3.6 KB First seen: 2022-12-06
MD5: be3b9a7ca16d063b9b2b3c132edb0f79 SHA-1: 045318816244ba901aeb001c114ec5d97b18b6cd SHA-256: 6841bbfdc2ef1768e7b3bca495a17b425726362e086456be2e0ba97a16c97852
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains an embedded OLE object that triggers the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for arbitrary code execution, likely to download and run a second-stage payload. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this known vulnerability.

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_off00000074.bin
da611fc46b7fa9a9f550ee29e5ac492e52ec6cec9efdf4b669a2bc646d7c1681		 rtf-objdata-decoded RTF \objdata at offset 0x74 1742 bytes

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