Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 fc65e3ab111f9197…

MALICIOUS

Office (OLE) / .XLSX

94.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-24
MD5: 1e6084be32c92360167d1bb19eb9c638 SHA-1: 1dc382b26b0997aceea08e5dc2fbbffb3ae38bcc SHA-256: fc65e3ab111f91977cd42adfdf95add38efbaa5c503f004f04fd576d5e93b907
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open function that is designed to execute dangerous formula APIs. ClamAV identified this as Emotet, a known downloader. The macros likely download and execute a second-stage payload from one of the embedded URLs.

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-b2cbc93e36c0c13e-9950560-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b2cbc93e36c0c13e-9950560-0
  • 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
2ca0966e93dacad101ceb18f4d58731b5432892fe851526f2fda59486181312c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7325 bytes

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