Malicious RTF — malware analysis report

Static analysis result for SHA-256 335a66f33efb9347…

MALICIOUS

RTF

4.6 KB First seen: 2019-12-10
MD5: bd57f39167db1a5bd55e18318dcdaa42 SHA-1: 6cfd2577fdc27c0c794d8cc5faf7310920814261 SHA-256: 335a66f33efb934713c602fcb011436d54f9f9bb3d248b977e0a1c6e0a0af4fc
200 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data and specifically triggers the Equation Editor vulnerability (CVE-2017-11882). This indicates the file is designed to exploit a client-side vulnerability for code execution, likely delivered as a spearphishing attachment.

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_off000000df.bin rtf-objdata-decoded RTF \objdata at offset 0xDF 2052 bytes
SHA-256: 692035b84c013b276ddb1b4af1f1c2844fc7171a6caf872f9200aedb62fc999c

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