Malicious RTF — malware analysis report

Static analysis result for SHA-256 7738264a6f987b86…

MALICIOUS

RTF

122.8 KB First seen: 2020-06-02
MD5: 51be8c61ea1b66a8c712f54f6788c6dc SHA-1: 3d5d07a6c558f698a1c8078474036a2db90ae89f SHA-256: 7738264a6f987b863e0a542d86c1da43d2ef3c456224fbe8cfc782c508733d29
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that triggers an Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for the execution of arbitrary code upon activation, likely leading to the download and execution of a secondary payload. The file is classified as malicious due to 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.
  • \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_off000002fd.bin rtf-objdata-decoded RTF \objdata at offset 0x2FD 43015 bytes
SHA-256: da89ec3cc650e49689083e928813105ffd5c8dc3d163d111be568c61566eb846

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