Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 4fb203958dc23dba…

MALICIOUS

Office (OLE) / .XLSX

217.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2023-02-11
MD5: b624c8a63e3b48f4351543fab0cd718f SHA-1: a0ebd1f6b5d816fa46e5c8e4c9dc41b349e3ad66 SHA-256: 4fb203958dc23dba23634f6f5356931bfc221e22bed0a184cd73153fca697a51
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1059.001 PowerShell: PowerShell T1566.001 Phishing: Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. ClamAV detection identifies it as an Emotet downloader. The macro's use of the RUN function indicates it is designed to download and execute a secondary payload.

Heuristics 4

  • 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.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • ClamAV: Xls.Downloader.Emotet-b649c93692b4c9d9-9976616-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b649c93692b4c9d9-9976616-0
  • 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.

FilenameKindSourceSize
xlm_macros.txt
0edbe25b38accd20142a8e93c6b5b55db50b2a332c7c6fb6cbfb60dba31b6951		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8308 bytes

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