Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 729173682e13a688…

MALICIOUS

Office (OLE) / .XLSX

114.0 KB Created: 2022-01-24 14:50:55 Authoring application: Microsoft Excel
MD5: 1863e7a220212010561fc0d1f71c0a5c SHA-1: be4cae474d10565ff9d906e630ae4c5e1cc0b5cb SHA-256: 729173682e13a688d1013356e52eea23e1bacb8e1b4a017d448ea4604979cf7c
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 defined name, which is a known technique for executing malicious code. ClamAV detection identifies it as 'Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0', strongly suggesting Emotet family involvement. The Auto_Open macro likely serves to download and execute a secondary payload, consistent with Emotet's downloader functionality.

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
f65423032a2492710482664c048191ebe835ee4ace2752f1b0fa6e40d416cdf9
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 4885 bytes