Emotet Office (OLE) / .XLSX malware analysis — malicious · 4a4ee3f8e96ff14a

MALICIOUS

Office (OLE) / .XLSX

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

MD5: c489ae0c647f3e828ee9d0db0f015252 SHA-1: 47c00172666c6219a694b7837c423904de9cbbc7 SHA-256: 4a4ee3f8e96ff14a83d4f61b0c94a52dab1ed3a0bcd3d588cfc52606df19d1d4

140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_AUTOOPEN_DEFINEDNAME indicate the presence of an Excel 4.0 macro with an Auto_Open entry, a common technique for Emotet. ClamAV detection further supports this attribution. The macro sheet contains an Auto_Open defined name, suggesting it is designed to execute automatically when the spreadsheet is opened, likely to download and execute a secondary payload. The document body content appears to be a lure for tracking blood pressure data.

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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