Malicious RTF — malware analysis report

Static analysis result for SHA-256 55ac5e9c28d1ee98…

MALICIOUS

RTF

20.2 KB First seen: 2020-08-25
MD5: a3ab7c518d5d802805b4a37442a20d1e SHA-1: 5ab864e44fbd448ee4fe22d860ccef32df8a32ff SHA-256: 55ac5e9c28d1ee983ca2c4cc08f24ccac927426e35e80ea699a8ea91671c9c98
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that triggers the CVE-2017-11882 vulnerability. This exploit is known to be used for client-side execution, typically to download and run a secondary payload. The specific ProgID 'eQUatioN.3' is indicative of this exploit.

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.
  • \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_off00002170.bin rtf-objdata-decoded RTF \objdata at offset 0x2170 1832 bytes
SHA-256: e10c40abba44192d4d7af4d8cb7d35e3e41af4bec97a5caca3748f5aa2f20635

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