Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 82b283aeb993f5b0…

MALICIOUS

RTF / .DOC

3.4 KB First seen: 2022-11-28
MD5: f2ad63734caf65b0ae201f24bc531101 SHA-1: 39d596d4d6f73a8d47c093284fde51f52f801035 SHA-256: 82b283aeb993f5b0521d96b01186522304b978479c10fca8ccb2ae776e5f38f2
200 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that leverages a known vulnerability in Microsoft Equation Editor (CVE-2017-11882). The presence of RTF_OBJAUTLINK, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this vulnerability for arbitrary code execution. The file is likely a dropper or initial access vector for further malicious activity.

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_off0000007f.bin
ed3fa67fb6f687a19a08a776c200ccd1108ded2282ff1c87c2a1edf8e4cd4d64		 rtf-objdata-decoded RTF \objdata at offset 0x7F 1629 bytes

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