Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 b8052965a72c6d91…

MALICIOUS

Office (OLE) / .XLSX

143.3 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 754d9d95afb3ca7d284c0545b276a55a SHA-1: d6cfe7b169e4023343d2cd29443d63b84edde8f9 SHA-256: b8052965a72c6d919d756cbca20b7143c23e32fb256708659872037d154b5cfc
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for Emotet to execute malicious code upon opening. The critical heuristics indicate the presence of dangerous formula APIs like RUN, suggesting the macro is designed to download and execute a secondary payload. ClamAV also identifies the file as Emotet. The document body, a time card, is a common lure for macro-enabled documents.

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-bd646319c2d29cd6-9951195-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0
  • 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
46284ea41c691066b9fe85a87bc7e9bfc77336182ea3b4ed700574b0c8cd3189
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3141 bytes