Malicious RTF — malware analysis report

Static analysis result for SHA-256 b15affecaf80efda…

MALICIOUS

RTF

8.6 KB First seen: 2020-08-25
MD5: f2e1cb6ab7fc7d1055f2250bf5f89704 SHA-1: ff99647be4c08f5ec0fd94638a91d9596eea456f SHA-256: b15affecaf80efdaf1245baa934f6207d63174e27d02b2bbc4e61939d92125cf
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, specifically related to Microsoft Equation Editor. High-confidence heuristics indicate the exploitation of CVE-2017-11882, which allows for arbitrary code execution. This technique is commonly used to download and execute further malicious stages.

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_off0000150c.bin rtf-objdata-decoded RTF \objdata at offset 0x150C 1484 bytes
SHA-256: 0a3a3f20b7969a8b67db91755f42f47de67d32d82d31bb3215207a535a821f16

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