Malicious RTF — malware analysis report

Static analysis result for SHA-256 f1b3411a41d57b00…

MALICIOUS

RTF

60.8 KB First seen: 2019-12-10
MD5: 6b10d550259c604c2bc16a216848359b SHA-1: ce4bc492555fe3c869f8e35f00b690d06d8f4dc1 SHA-256: f1b3411a41d57b001cd3cfbb977b2cb7dde62a1ce8fd7fa645a17cd3555f42e5
120 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object with a suspicious ProgID, indicative of an Equation Editor exploit. The \objupdate directive forces the activation of this object, triggering the exploitation of a client-side vulnerability. This technique is commonly used to download and execute a secondary payload, hence the high confidence in this attack pattern.

Heuristics 3

  • 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.
  • \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_off0000ab7f.bin rtf-objdata-decoded RTF \objdata at offset 0xAB7F 1793 bytes
SHA-256: 090017ab7bc28f122cd8437d0ec4b9812e970505d5159db7d8866ad4f8ca43de

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