Emotet Office (OLE) / .XLSX malware analysis — malicious · 489a8d75e0335e05

MALICIOUS

Office (OLE) / .XLSX

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

MD5: 6344d7b926677715b9b9d9444edba5bf SHA-1: 1079f25db8b032c4422f0b0a25b6f1cdec46a2e9 SHA-256: 489a8d75e0335e05d649b0e5cae103a142020fe00909e4e1f2d83704f07fff84

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 entry, a known technique for Emotet. ClamAV detection further supports this attribution. The document body, while appearing benign as a blood pressure tracker, is a lure. The Auto_Open macro is designed to execute automatically upon opening the spreadsheet, likely initiating the download of a secondary malicious 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.
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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