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

Static analysis result for SHA-256 fde6d0dd2f071d53…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:46:25 Authoring application: Microsoft Excel
MD5: 51fcf12f55409c5ede2b8da2f3fb4c4f SHA-1: 3a8030a4374c69fee9ed3db3fc36e7b1f6449a8c SHA-256: fde6d0dd2f071d533aea58f7b85c45289f3b367e0a62101db6abf73f3cd8c3b7
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a known technique for executing malicious code upon opening the workbook. The heuristics indicate the use of dangerous formula APIs, including the RUN function, suggesting the macro is designed to execute arbitrary commands. No specific family could be identified, but the technique is common for initial access or payload delivery.

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
6858d6e4f80cdf9ded3d0eb19eb5ada7166de8d614dd0dab59d074c772149480
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6528 bytes