Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 fd287d6a57e77d59…

MALICIOUS

RTF / .DOC

52.7 KB First seen: 2023-09-07
MD5: 90b04103a976e5278a83054178f56e6f SHA-1: 9d2bfb16893d96b0b7cb1b9a5684d13fdb98deb6 SHA-256: fd287d6a57e77d596c51fb7a53682274eb1ee0dd111fb466183b2bb5eda8342a
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution T1204.002 Malicious File T1566 Phishing T1566.001 Spearphishing Attachment

The sample is an RTF document that contains an embedded OLE object, specifically leveraging the Equation Editor vulnerability. The document body provides a lure about financial auditing, instructing the user to 'click Enable editing', which is a common tactic to bypass macro security. The presence of RTF_OBJDATA, RTF_OBJEMB, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristics strongly indicates exploitation of an OLE object vulnerability, likely to download and execute 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_off00002ff0.bin
cc09ce1871159f530183c561077a2c43a2dcf9dfa3fc9c82338d7e4271aaecf5
rtf-objdata-decoded RTF \objdata at offset 0x2FF0 1696 bytes