Office (OLE) / .XLSX malware analysis — malicious · 315372d68f1a20f0

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:46:59 Authoring application: Microsoft Excel

MD5: 03448b5f0486fb859184a1e8dbda42da SHA-1: eb19036b9832efc92f8c2cb8342c90173b6f8500 SHA-256: 315372d68f1a20f0c33996affa7f05c1a73b421486699fda773e4a238cb9ac0c

140 Risk Score

Malware Insights

MITRE ATT&CK

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

This Excel file contains Excel 4.0 (XLM) macros, specifically an Auto_Open defined name. The presence of a dangerous formula API, identified as 'RUN=0', indicates that the macro is capable of executing arbitrary commands. This is a common technique for downloading and executing a second-stage payload. No specific IOCs were extracted, but the technique itself is highly indicative of malicious intent.

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` `c6e1b2c6cd3313c79c03d7e9b06b02703287abe238444d525fc5bbfb017281d3`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6587 bytes

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