Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a991016eb3f11c42…

MALICIOUS

RTF / .DOC

24.4 KB First seen: 2022-12-29
MD5: e5ef96be911a49b508f07f10653e972a SHA-1: f34d17344b45f7009fa84fe73abece61238e4278 SHA-256: a991016eb3f11c42098fdf93732cef23a53ae77bf89242a0369e48973fa1b043
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1059.005 Exploitation for Client Execution: Visual Basic

The file is an RTF document containing an embedded OLE object that leverages the Equation Editor vulnerability. The document body contains a lure instructing the user to 'Enable editing', which is a common technique to bypass macro security settings. The presence of RTF_EQUATION_EDITOR and RTF_OBJUPDATE heuristics strongly suggests exploitation of the Equation Editor 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_off00004481.bin
65a4bc59ade8eb146ab6bb13ee2caafd606a6316086c4392fe063661d8559104
rtf-objdata-decoded RTF \objdata at offset 0x4481 1817 bytes