Malicious RTF — malware analysis report

Static analysis result for SHA-256 258f1703a4b4d438…

MALICIOUS

RTF

25.2 KB First seen: 2023-05-18
MD5: 25fb7bbf19fd1cec0c0128c0dfe6fdb2 SHA-1: 857f743601c70c5310f0b63a69a4359ecf19757b SHA-256: 258f1703a4b4d4382f0e3ae4c25500f7ee9d9dece9b6285073bf74c6259b47da
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

The RTF document contains heuristics indicating the presence of an embedded OLE object, specifically targeting the Equation Editor vulnerability. The document body includes a lure to 'Enable editing', which, when acted upon, would likely trigger the embedded object's activation via \objupdate. This suggests the file is designed to exploit the Equation Editor to download and execute a secondary payload.

Heuristics 5

  • 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 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_off000043d9.bin
c332252340987a879515d488023c05407828dd95c10a7adadf82b3ec5856f93d
rtf-objdata-decoded RTF \objdata at offset 0x43D9 1413 bytes