Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a78f33c16f2dda00…

MALICIOUS

RTF / .DOC

8.8 KB First seen: 2022-03-14
MD5: 7e923f9ed71605c75cec4a39d9ae9115 SHA-1: e298bd1e7090016119eb69d8eaa158b04046026a SHA-256: a78f33c16f2dda006e42cd86aa82adb522c24c9bd2c7583c70007a8a58649b07
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell

The RTF file contains embedded OLE objects and specifically targets the Equation Editor vulnerability (CVE-2017-11882). The critical heuristic 'RTF_EQUATION_EDITOR' and high heuristic 'CVE_2017_11882_ACTIVATION_RELATED' strongly indicate exploitation of this known vulnerability. The embedded object's ProgID 'EQUATIOn.3' is a key indicator for this exploit. The attack pattern involves leveraging this vulnerability to achieve arbitrary code execution.

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 2 \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_off00001396.bin
c7e72c5a9e0fde037426fef4288fb46f4ae5950dc2be8c83185692af56a2c356		 rtf-objdata-decoded RTF \objdata at offset 0x1396 1911 bytes

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