Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 9383f5429dbc6fab…

MALICIOUS

RTF / .DOC

31.8 KB First seen: 2023-05-05
MD5: 6525097473be789d1b0aaf67a73d6dce SHA-1: 4b6820b70e6d62e587e4bea8f44911f9492a1d47 SHA-256: 9383f5429dbc6fabadceff1de450a2dedba1dbdbe550b5a58a60bf0fe038740d
160 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that leverages a known Equation Editor vulnerability (RTF_EQUATION_EDITOR). The presence of \objupdate indicates that the OLE object is designed to be activated automatically upon opening, bypassing user interaction for exploit execution. The document body contains a lure to enable editing, further supporting a malicious intent.

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_off00005c1b.bin
59fed4d68eeff2426e4b68fc94fd50cc16aded1b2f0d1e481f9c392c658419e8
rtf-objdata-decoded RTF \objdata at offset 0x5C1B 1500 bytes