Malicious RTF — malware analysis report

Static analysis result for SHA-256 61e9cdbd40d2e092…

MALICIOUS

RTF

169.4 KB First seen: 2019-08-04
MD5: 9d974694a137878e1ecf519796fcaee0 SHA-1: 2fd310ac0e6c2f106bf4a4b2348c6cf2a3c3ed7e SHA-256: 61e9cdbd40d2e0929cd1f71e207d52083f457c3f2a4adc90241fe46a7ed20bb8
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, a known vulnerability that allows for arbitrary code execution. This technique is commonly used to deliver secondary payloads, hence the high confidence in this attack pattern.

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_off00006784.bin rtf-objdata-decoded RTF \objdata at offset 0x6784 41705 bytes
SHA-256: 6b43fbe430e9dda58c1feab39f29d6d8d5b3df763e3dd2de81cca2af474ba3cb

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