Malicious RTF — malware analysis report

Static analysis result for SHA-256 3b406d1a5764d2b2…

MALICIOUS

RTF

41.0 KB First seen: 2023-07-21
MD5: 1807759e6b03e69780dd6775b44e03fd SHA-1: 9e2ec8744b87c9903364090f4752505457dbfcae SHA-256: 3b406d1a5764d2b20c36bb714c3c5d1e016d59bf4d6371667b61a3d8686a3071
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.005 Service Execution: Visual Basic

The RTF document contains an embedded OLE object with an Equation Editor ProgID, a known vector for exploiting vulnerabilities like CVE-2017-11882. The \objupdate directive forces the activation of this object, triggering the exploit. The document body contains a lure to "Enable editing", common for macro-based malware, but the primary threat here is the Equation Editor exploit which is designed to execute arbitrary code, likely for a secondary payload download.

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_off0000478a.bin
017f5cac7db5f0a397b9fc2a1f4e21b419e50091309e414ac4a1b020dd8a6dd4
rtf-objdata-decoded RTF \objdata at offset 0x478A 1785 bytes