Office (OLE) / .XLSX malware analysis — malicious · 43db5746bc7bddb5

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:43:55 Authoring application: Microsoft Excel

MD5: 5fa0a9494c38dbd524aa17391f9838c3 SHA-1: 9550dc149eb311df4d2ffb85cbc8cdb6adcd07a4 SHA-256: 43db5746bc7bddb5ac3b5a2e8c8104085a5a3e1fdf054e10a79c5bf6e008c342

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The sample is an Excel file containing Excel 4.0 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 upon opening the workbook. The dangerous formula API 'RUN' was identified, which is commonly used to execute arbitrary commands. This indicates the file is designed to download and execute 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` `a0b52f488e067bac31b2a5ec98980830a29fd634d2b9e20d9121b7f52ba332e6`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6714 bytes

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