Emotet Office (OLE) / .XLSX malware analysis — malicious · 54c4606892b1fede

MALICIOUS

Office (OLE) / .XLSX

141.1 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel

MD5: 40fd1afbbbf501d3631eaf793dd7697e SHA-1: 85773db1aa5f0a752caf513e16d4eff92ccc06c6 SHA-256: 54c4606892b1fede80e10591041b980262e6a780b2017de3ce6779d96d862a44

140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open defined name, a common technique for Emotet. ClamAV detection further supports this attribution. The macro sheet itself appears to be a lure, presenting itself as a blood pressure tracker, while the underlying XLM macro is designed to execute automatically upon opening. The primary function of this macro is to download and execute a secondary payload, consistent with Emotet's typical behavior.

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.
ClamAV: Doc.Downloader.EmotetExcel01220-9936774-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Doc.Downloader.EmotetExcel01220-9936774-0
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` `592af8991900f2f7058dc7ea90a33320ae293c7e541db4222a7b7f9c04f59d96`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	8469 bytes

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