Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c4988acded3e37f0…

MALICIOUS

RTF / .DOC

25.1 KB First seen: 2023-04-06
MD5: ec0b766b76636ff53fb442c934853ccc SHA-1: f1792b1dc156878b48002d675608dd5d9098a47c SHA-256: c4988acded3e37f05fa2b708d5057e5727c23f18263d09b36ddd408366abc472
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.001 Malicious Link: Malicious Link T1059 Command and Scripting Interpreter T1566 Phishing T1566.001 Phishing: Spearphishing Attachment

The sample is an RTF document containing an OLE object that exploits the Equation Editor vulnerability. The presence of RTF_OBJDATA, RTF_OBJAUTLINK, and RTF_OBJUPDATE heuristics strongly indicates the exploitation of a known vulnerability to trigger the execution of embedded malicious content. This pattern is commonly used to download and execute a second-stage payload.

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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000d2e.bin
3a712b399c758f4fe8811fc87f7368df8708550fc003091eff9b2b1af16c30ec
rtf-objdata-decoded RTF \objdata at offset 0xD2E 1654 bytes