Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 adc1239705e03941…

MALICIOUS

Office (OLE) / .XLSX

143.0 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 08325540edfe15ab23a91ba50d3d093b SHA-1: 574619219550e1e0a5f475997a49a6d446034941 SHA-256: adc1239705e03941afe65a1c7fa1ae3a7c07a473c718a0e987c97dff4461bb62
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is an Excel spreadsheet containing Excel 4.0 macros, specifically an Auto_Open macro. This macro is flagged as dangerous due to its use of the RUN API, indicating it's designed to execute arbitrary code. ClamAV identifies the file as 'Xls.Downloader.Emotet', strongly suggesting it's part of the Emotet botnet infrastructure. The macro's purpose is to download and execute a second-stage 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-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