Office (OLE) / .XLS malware analysis — malicious · b488e96e5403f73b

MALICIOUS

Office (OLE) / .XLS

36.5 KB Created: 2020-11-27 11:43:20 Authoring application: Microsoft Excel

MD5: 482ca668733925c391419fc7d4fd56ad SHA-1: 3fd18bb19a7815dee0d03be7a1d0759e3780e26e SHA-256: b488e96e5403f73b44c169fa2dc9489444c01ac1e9400106be215b813609ab8a

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell

The sample is an Excel file containing Excel 4.0 (XLM) macros. A critical heuristic identified an Auto_Open defined name, indicating that the macro will execute automatically when the workbook is opened. The presence of the Auto_Open function, combined with the use of dangerous formula APIs like RUN, strongly suggests the macro is designed to execute arbitrary commands, likely to download and run 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` `47044d9e585eb4637a875d89398d6a82c49b8a5334db444c2bc4f26028628452`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	7009 bytes

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