Malicious RTF — malware analysis report

Static analysis result for SHA-256 943ff049c4bebe62…

MALICIOUS

RTF

4.1 KB First seen: 2021-06-20
MD5: a190dcd0d36b42dc5dbb2310d618b4d6 SHA-1: 3fe2c6e7c2e1ae62159168f4cc85a3e547b0eab2 SHA-256: 943ff049c4bebe62098e73bb6e8ac5d9e5c6b5ed9c015cee46ef485682e43143
200 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. This indicates the document is designed to exploit a known vulnerability in the Equation Editor component to achieve code execution upon opening. The presence of ".objupdate" further suggests an attempt to force OLE object activation.

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.
  • 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 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000090.bin rtf-objdata-decoded RTF \objdata at offset 0x90 1833 bytes
SHA-256: 4fde6bf17c6012049bd3d301c86b056dea08d221b72371df8aaa173e4ff223b8

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