Malicious RTF — malware analysis report

Static analysis result for SHA-256 1a8ea48512a14755…

MALICIOUS

RTF

25.6 KB First seen: 2023-01-04
MD5: 61a218e788d00d656ceab2a3bfa944bb SHA-1: a9c357623f874338c79f7e17852bf4979493e123 SHA-256: 1a8ea48512a14755b40f62b28777f81778c32882ff98821dd858e98eae667191
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The RTF document contains an embedded OLE object with a split Equation Editor ProgID, indicating an attempt to exploit the Equation Editor vulnerability (CVE-2017-11882). The \objupdate directive forces OLE activation, and the SE_ENABLE_LURE heuristic suggests the document prompts the user to enable editing or macros. This combination strongly suggests the file is a dropper designed to exploit this vulnerability to execute a secondary payload.

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_off00004c8b.bin
6a2afd8b1b772854567330a2c469cee50202388b5be1d54133efa68164ef0bf8
rtf-objdata-decoded RTF \objdata at offset 0x4C8B 1175 bytes