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

Static analysis result for SHA-256 5fd43cd24e2a886f…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:39:58 Authoring application: Microsoft Excel
MD5: 63c43c6b18a4e044ccfb566ff42c4e4d SHA-1: d680e2254e21f563ad525369c59d4ed7db12fa87 SHA-256: 5fd43cd24e2a886f1f4837f20df6dab9f96716d01d768e785943ccec6f3a6a2f
140 Risk Score

Malware Insights

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

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open macro. This indicates an attempt to automatically execute code when the workbook is opened. The presence of dangerous formula APIs like RUN suggests the macro is intended to download and execute a second-stage payload, a common technique for malware 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
55384177053acad9fe512c6c7be4577a0a95fb99e9514bdb06c5bb7ca6c6732e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6928 bytes

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