Office (OLE) / .XLSX malware analysis — malicious · 4c85eeb11f7bcd36

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-30 17:38:24 Authoring application: Microsoft Excel

MD5: 5ab314c82d63ae8f3c68b01bad4ca7d0 SHA-1: c0157695c389f574d127a024bdc65d1d776be804 SHA-256: 4c85eeb11f7bcd36eb1449ea25a11ad15313e8f1b8427c8d027d396ccaa1469a

140 Risk Score

Malware Insights

MITRE ATT&CK

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

The critical heuristic OLE_XLM_DANGEROUS_FN indicates the presence of an Excel 4.0 Auto_Open macro that utilizes dangerous formula APIs, specifically the 'RUN' function. This strongly suggests the macro is designed to execute arbitrary commands upon opening the spreadsheet. While no specific URLs or hashes were extracted, the 'RUN' function itself is a critical indicator of malicious intent for initial execution.

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` `1fd01b59df06e927b5429d60c4b6d3f9efad37a1d697f990d7ffc97deac1576c`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6696 bytes

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