Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 3bdcf16e51e0ab7b…

MALICIOUS

Office (OLE) / .XLSX

142.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-25
MD5: 0d9ed96a822b06bc54377748fd0105be SHA-1: 87381254783063975969782998a6fd11b6ef2143 SHA-256: 3bdcf16e51e0ab7bdeddae5aa43826ff747156a6b905737671acdc491b5853a2
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The sample contains Excel 4.0 macros, specifically an Auto_Open macro, which is a known technique for delivering malware. The heuristics indicate the use of dangerous formula APIs like RUN, suggesting the macro is designed to execute code. ClamAV detection confirms this as Emotet. The macro likely downloads and executes 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-adc2d23d2dc26dd0-9950240-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-adc2d23d2dc26dd0-9950240-0
  • 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
eee0a3dec225fd0088c74c7ab34b064dd06b0d4f7198f4d9a113e7b902ce722a
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6706 bytes