Office (OLE) / .XLSX malware analysis — malicious · 26011a5fcb80b988

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:43:42 Authoring application: Microsoft Excel

MD5: 5bc19214e48d6bb39f68d89e6a86e4af SHA-1: 367dd05ed507a6cce26cacb433c9fc1cc179f39a SHA-256: 26011a5fcb80b98886dc0d2cafc0b76d8a7e82b5f7e204a6849eb34b770ae4e5

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell

This Excel file contains Excel 4.0 (XLM) macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristic firings. The presence of an Auto_Open defined name suggests that the macro will execute automatically when the workbook is opened. The dangerous formula APIs, specifically 'RUN', are used, which allows for the execution of arbitrary commands. The macro sheet is named 'QyHFRrkrs', and the Auto_Open entry points to cell G175.

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` `012f5d5fd2cf8d675194fc02d408ce989738beee2bd2a2d675b7e8d80db6c6b1`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6743 bytes

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