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

Static analysis result for SHA-256 14339217815a140f…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:39:57 Authoring application: Microsoft Excel
MD5: 84f33d4b41ad5be19a86d41796881d75 SHA-1: 9a3d8af979418c4ee492dba19464cc8c0038f00f SHA-256: 14339217815a140fc0496de55bbc182f58b7f1caafd9e4047997ee0616d5d7a9
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing an Excel 4.0 macro sheet with an Auto_Open defined name. This indicates the file is designed to automatically execute a macro upon opening. The presence of dangerous formula APIs like RUN suggests the macro is intended to execute arbitrary commands, likely to download and run a second-stage payload.

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
bcdda8233b8ace8fb982afdda6be153ecfaf42f77ab46f702c344f07a86b98ef		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6398 bytes

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