Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 76a8a187cb83651a…

MALICIOUS

RTF / .DOC

40.4 KB First seen: 2023-06-14
MD5: a4b441dc077059150c6a09a3a54ec5af SHA-1: 58cfa02b1d9cb735b6beba781101223612ffe885 SHA-256: 76a8a187cb83651ab2df6370985f5a63ada5db7c145c33f17da4b37dbafd9186
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution: Malicious Link T1059.005 PowerShell T1204.002 User Execution: Malicious File

The file is an RTF document containing an embedded OLE object, specifically targeting the Equation Editor vulnerability. The document body includes a lure instructing the user to 'Enable editing', a common tactic to bypass macro security. The presence of RTF_EQUATION_EDITOR and RTF_OBJUPDATE heuristics strongly suggests exploitation of this vulnerability, likely leading to the download and execution of 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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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_off00004af6.bin
3685fff3f34cb685357bcc5428257736174b10bc9a28ed54240c16d401c15859
rtf-objdata-decoded RTF \objdata at offset 0x4AF6 1651 bytes