Office (OLE) / .XLSX malware analysis — malicious · 3e8a351a7cde4607

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 17:48:20 Authoring application: Microsoft Excel

MD5: 3ae66b2d680df641745fa9ee29a3f317 SHA-1: b5646c4bdc3f6b2b3f3b49dd08500b0bc775fb08 SHA-256: 3e8a351a7cde4607748e434454795167698651e1b0fb6917c1c56832d2c7229f

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1059.001 PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The heuristics indicate the use of dangerous formula APIs, including the RUN function, suggesting the macro is designed to execute arbitrary commands. The presence of the sheet name 'gxUUp' might be an indicator or part of the execution chain. The macro sheet is likely responsible for downloading and executing 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.

Filename	Kind	Source	Size
`xlm_macros.txt` `ea3827d428c630cf785b83647adac8f28c88236fc63656e2df23cee18722bbe2`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6433 bytes

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