Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 39a535eac490218b…

MALICIOUS

RTF / .DOC

39.4 KB First seen: 2022-12-19
MD5: a84ad77f6b05082e8246dad37d1392ac SHA-1: a3a4f55bb83ee179166ec7f60b7bf5e41b26ee0e SHA-256: 39a535eac490218b493be8b0ef428840a84c113b4962b5da8a884fe7a5ca0f2a
140 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 that contains an embedded OLE object with a specific Equation Editor ProgID, indicating an attempt to exploit the Equation Editor vulnerability (CVE-2017-11882). The \objupdate directive forces the OLE object to activate, triggering the exploit. The document also contains a lure to enable editing, a common tactic for macro-based malware.

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_off000082b9.bin
ca917002ec7dff4cf5fc1cf36834ccc9f2e6a92daa3f869c1e18f2d1e77aff90
rtf-objdata-decoded RTF \objdata at offset 0x82B9 1511 bytes