Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 47f7f99f89aa7b1e…

MALICIOUS

Office (OLE) / .XLSX

143.1 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: b5816a9b7e5e698febd06d6bddc9cafc SHA-1: 1c58a0ff19bca4b7e2af487f6c41b552b417750a SHA-256: 47f7f99f89aa7b1e0d90d7f1037497c78d9dcf72fa7e3d298d1f221f2456a816
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. ClamAV identified the file as 'Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0', strongly suggesting it acts as a downloader for the Emotet banking trojan. The macro uses dangerous formula APIs, including the RUN function, to initiate the download.

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