Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 c742edfa3f3c8c00…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:38:40 Authoring application: Microsoft Excel
MD5: ea3e27423d27e814911ed9fa22196a61 SHA-1: c5f2a20d6451b772d1ec965f3efcd8b0fbc3b9f9 SHA-256: c742edfa3f3c8c002220de5b08d245b0c3a2d064084052bae706e120628d2d41
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The heuristics indicate the use of dangerous formula APIs, including the RUN function, suggesting the macro is designed to execute arbitrary commands. This is a common technique for initial payload delivery in macro-based attacks. No specific family could be identified, but the technique is indicative of a downloader or initial access stage.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
c1a213135357a5bee8b7d92821ee7e60b4d04300cc064ff6aca282b6e77c1821
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6460 bytes