Emotet Office (OLE) / .XLSX malware analysis — malicious · d99da3f8ba8f43fe

MALICIOUS

Office (OLE) / .XLSX

141.2 KB Created: 2022-01-18 14:11:14 Authoring application: Microsoft Excel

MD5: 316c00d22a6e6095580829e43a47c18e SHA-1: f1c3a6c048d9e61071a8a965379e8a7ab9f13852 SHA-256: d99da3f8ba8f43fe489d430688fc0c98117d58a36c708fc038cbefd530d16e61

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 Excel 4.0 macros designed to auto-execute. ClamAV detection further confirms this as 'Doc.Downloader.EmotetExcel01220-9936774-0', a known Emotet downloader variant. The macro sheet contains an Auto_Open entry, which is the primary mechanism for executing the 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` `c355a4e8b51815f97cf3e202ab7d47ce16f5f701c419b0e7a11ef751a8ea709e`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3661 bytes

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