Malicious RTF — malware analysis report

Static analysis result for SHA-256 d4d857e576e5c325…

MALICIOUS

RTF

354.8 KB First seen: 2019-08-04
MD5: 52bd8d12d273767ca02b3376657f3919 SHA-1: 87d8ef55a04eb935296fd7aca8b28384e1bd4711 SHA-256: d4d857e576e5c325c0a93398a3f63f46d9e4b633ff035ddb6d4f7066da35fab0
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains an OLE object that leverages the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This vulnerability allows for the execution of arbitrary code upon activation of the embedded object, likely leading to a second-stage payload download or execution. No document body text or scripts were extracted, but the critical heuristic firings strongly indicate exploitation.

Heuristics 5

  • Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • 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_off00000298.bin rtf-objdata-decoded RTF \objdata at offset 0x298 106919 bytes
SHA-256: d5128a5963cac68aa1d37988a371f00ace6ac028416c1430e306e118fef9ea8a

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