Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 5f8573d933fb9af9…

MALICIOUS

RTF / .DOC

26.4 KB First seen: 2023-01-05
MD5: 051873c5ce8770dd82270d6ac13e3061 SHA-1: ac83d6b235460fb3516e0efb7b91d2159ab4636e SHA-256: 5f8573d933fb9af96a8e7fb3ad4083e7d5fdad2c4a5960b7dc7f79bb788b6658
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution: Malicious Link T1059.005 PowerShell

The sample is an RTF document containing an embedded OLE object, specifically targeting the Equation Editor vulnerability. The document body contains a lure instructing the user to 'Enable editing' to view its content. The presence of `RTF_EQUATION_EDITOR` and `RTF_OBJUPDATE` heuristics strongly suggests exploitation of CVE-2017-11882. This exploit likely leads to the execution of a secondary payload, indicated by the `RTF_OBJDATA` firing.

Heuristics 4

  • 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
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00004c87.bin
351caebcd5142af99f75771f3f9dd6b7870345f85992fcae7e382cb6cad8e52d
rtf-objdata-decoded RTF \objdata at offset 0x4C87 1348 bytes