Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 6b33ac5a401a40c9…

MALICIOUS

Office (OLE) / .XLSX

114.6 KB Created: 2022-01-24 14:50:55 Authoring application: Microsoft Excel
MD5: 982e0ddc0af31f8cf533bc093afafe9c SHA-1: 8a31ce510a8ca014196d29cc6716a0714739d023 SHA-256: 6b33ac5a401a40c976fbb18548708c1b07405a7d560e6f485cf7efe5c6b03f79
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 identifies this as Emotet, a downloader family. The macro likely executes a second-stage payload, consistent with Emotet's behavior.

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

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