Malicious RTF — malware analysis report

Static analysis result for SHA-256 d880675788d1cff4…

MALICIOUS

RTF

887.0 KB First seen: 2020-05-25
MD5: 1420210c3e9827f7e6c2b3ccfa5b3555 SHA-1: a6d56949e13c4c3ec8b0cf38e5a1e6af56c6a9c4 SHA-256: d880675788d1cff4bc0b11d4d4ff5527888662ee8387bd958a5ad74b819b2a7a
240 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data, specifically related to Equation Editor. Heuristics indicate the exploitation of CVE-2017-11882, which allows for arbitrary code execution when the embedded object is activated. The ClamAV detection as Rtf.Dropper.Agent-7701975-0 further confirms its malicious nature as a dropper.

Heuristics 6

  • 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.
  • ClamAV: Rtf.Dropper.Agent-7701975-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-7701975-0
  • \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_off0000082d.bin rtf-objdata-decoded RTF \objdata at offset 0x82D 100610 bytes
SHA-256: 150804688e74cd752b0705801bffc77667358ef7b7b1a10b92581de803a5ec7e

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