Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b159d4e94f3db24a…

MALICIOUS

RTF / .DOC

36.6 KB First seen: 2023-02-13
MD5: 3386d715eeed326e62df9653371d4313 SHA-1: 41c0882c487a2fcf4b689ef25853a1ce15cfffa5 SHA-256: b159d4e94f3db24a3cc68ef49fa4a6d2fa87fd55ae86e4980749740c9689c8b5
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Phishing: Spearphishing Attachment T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document containing an embedded OLE object, specifically exploiting the Equation Editor vulnerability (RTF_EQUATION_EDITOR). The presence of \objupdate indicates an attempt to automatically activate the OLE object, bypassing user interaction. The document body presents a plausible lure related to marketing strategy to encourage the user to enable editing, which would trigger the exploit.

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_off00004197.bin
d84b20c287b5a988e3aa57b10b9397dcc05c04d7d709a8c800b856b5862705f6
rtf-objdata-decoded RTF \objdata at offset 0x4197 1759 bytes