Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 1575974851d59dd4…

MALICIOUS

Office (OLE) / .XLSX

94.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-24
MD5: b120713a4b89a9d6489ce5b4f45e5998 SHA-1: b35e33565da9c72a75d0dcdd71900436cd4e67cb SHA-256: 1575974851d59dd453fa8ae8e1fef219cede4a2f84f5758f1a978a0ae64722f3
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is identified as malicious by ClamAV with the signature 'Xls.Downloader.Emotet'. Static analysis revealed the presence of Excel 4.0 macros, specifically an Auto_Open entry, which is a known technique for executing malicious code. The macros utilize dangerous formula APIs, including RUN, indicating an attempt to download and execute a payload from the provided 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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