Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 87f3a7f77e339c05…

MALICIOUS

RTF / .DOC

29.8 KB First seen: 2023-04-28
MD5: ceeec4b19f3ce7e46c6c5adcb2f40ffd SHA-1: 1c15a0b7650023bfafbeaf36afed4f2dae7ae210 SHA-256: 87f3a7f77e339c0572b9a2fe094c33028581c56bc9f17c3f83d3d62fc53662bf
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 exploits the Equation Editor vulnerability. The document body includes a lure to 'Enable editing', indicating a social engineering attempt to bypass macro security. The critical RTF_EQUATION_EDITOR heuristic confirms the exploit method, and the SE_ENABLE_LURE heuristic suggests a dropper or downloader functionality.

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_off00004548.bin
39831148130b0f3d7c661b8cb62d60f515ea50a163e90eaffaa21b7bcee26451
rtf-objdata-decoded RTF \objdata at offset 0x4548 1646 bytes