Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 79507cc2406fa626…

MALICIOUS

Office (OLE) / .XLS

114.6 KB Created: 2022-01-24 01:40:11 Authoring application: Microsoft Excel
MD5: 4afcb45b7ef442ac4a8250eff5bf4c3b SHA-1: 8a379a9dc8d0a98e6423ebc434908bdae587ec19 SHA-256: 79507cc2406fa626da2db0b0bd4ad0b6a21f593ec83b2cdb2a7b0fe299ce6f02
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is identified as malicious by ClamAV as 'Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0'. Static analysis revealed the presence of Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. The 'RUN' function API was also detected, indicating the macro attempts to run an executable. This combination strongly suggests a downloader functionality, characteristic of the Emotet family, designed to fetch and execute further malicious content.

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
86637063ac2c97bbefdbc9033f21cd30e9484ed274aba63ad50d62dfa1de93cd
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 4341 bytes