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

Static analysis result for SHA-256 6652ad064361b22a…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:44:47 Authoring application: Microsoft Excel
MD5: 08bb260b127229ea47409f819b82d996 SHA-1: 12d41376ad662f5ffc5e3578abdae830141ed8c3 SHA-256: 6652ad064361b22a00e888f3be8bdccbdb849b5118c96ec9982bb7aa0ac4427a
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, indicated by critical heuristic firings for OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN. The presence of an 'Auto_Open' defined name suggests that the macro is designed to execute automatically when the workbook is opened. This is a common technique for malware to download and execute a secondary 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
4158fc51a67fd9646f0743a48492a508e11b1059dff9db1c73ee19cc40660379		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6808 bytes

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