Office (OLE) / .XLSX malware analysis — malicious · 4fa70b36331b85c6

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:43:56 Authoring application: Microsoft Excel

MD5: b48f721b288266e546ea6ef911487bd7 SHA-1: be4bd22e332681353a6c24d35667ba12a920ba0d SHA-256: 4fa70b36331b85c66ffa729eecfd4383bb430d8d75f8420d5eb0c7296184e0c3

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Excel 4.0 Auto_Open macro. The critical heuristic OLE_XLM_DANGEROUS_FN further confirms that this macro uses dangerous functions, specifically the RUN function, which is commonly used to download and execute a second-stage payload. No specific family could be identified, but the technique is consistent with macro-based 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.

Filename	Kind	Source	Size
`xlm_macros.txt` `37bc01ccd89968750b0a601041c4a036fb8c3a346410ca876461e290959d898a`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6357 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.