Office (OLE) / .XLSX malware analysis — malicious · a6b8b633b4ef0a00

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:29:30 Authoring application: Microsoft Excel

MD5: 646a50395072ad8963a430c71ca71a24 SHA-1: 65f5c11c43eb638de7d7ef771b4ae734515fac46 SHA-256: a6b8b633b4ef0a00d656eccd7db1a2e9f8609d4e7020982223af8e7c0e6b2cc3

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1569.002 ShellExecute

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands. While the exact payload is not visible, the Auto_Open function is a common method for downloading and executing second-stage malware. No specific family could be identified.

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` `609d7e8e4819643aabd5a0c3d68258b1a34a0f60a8ea507f87ae82180745a53d`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6598 bytes

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