Malicious RTF — malware analysis report

Static analysis result for SHA-256 9b4aaafe19c4c5b3…

MALICIOUS

RTF

412 B First seen: 2021-06-17
MD5: 8258ff60352cce803b7a66c0a1b47f48 SHA-1: 56611dd1baa8550aaf68feb678bb192c93fde01c SHA-256: 9b4aaafe19c4c5b32e1ce7aa8c17f765af0a15f1baadbb5477c0905d0ab980ea
180 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The presence of \objupdate and the specific Equation Editor ProgID strongly indicate exploitation for client execution. The file is likely delivered as a spearphishing attachment.

Heuristics 5

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical 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.
  • \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_off000000c8.bin rtf-objdata-decoded RTF \objdata at offset 0xC8 77 bytes
SHA-256: f420ab242d3408a7dab387b0ac4ec31a4976ca44bf016ec4a4dd3eb9f84b05dd

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