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

Static analysis result for SHA-256 c7a9f801ad663b6a…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:01:50 Authoring application: Microsoft Excel
MD5: 75124238ef7bcc4ee2fb32742cdf5774 SHA-1: c500adf48cc885ccf2de1949dad8de4961e60e36 SHA-256: c7a9f801ad663b6a83e7b1be4899aa799413fc20eb7e5df562a08c20572dbe5b
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. This indicates that the macro sheet is designed to automatically execute code upon opening the workbook. The presence of dangerous formula APIs like RUN further confirms the malicious intent. The macro sheet itself is heavily obfuscated, but the Auto_Open trigger is clear.

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
d7023c6e4564101ad3c09c816ec8a193afe7dda1922bcd8e007cd9ac4a4b063e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6782 bytes

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