Office (OLE) / .XLSX malware analysis — malicious · be1ba87d29477511

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:45:00 Authoring application: Microsoft Excel

MD5: 072d826fd30287b49784860fa0631fdc SHA-1: 9764a547796b96754e92b6253640ee165a6acdd7 SHA-256: be1ba87d2947751138779192672fd84a8f170143089a0ef34cba6d17dcc8b6f6

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell

The file contains Excel 4.0 (XLM) macro sheets, specifically triggering critical heuristics for an Auto_Open defined name and the use of dangerous formula APIs like RUN. This indicates the macro is designed to execute arbitrary commands upon opening the spreadsheet. The presence of the Auto_Open function strongly suggests an intent to download and execute a secondary payload, a common initial access technique.

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` `86ef74bd84f304eca136df2be98fa8846069db3de33b728edb31b2fe1cede606`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6695 bytes

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