Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 1ffa8740eef2d512…

MALICIOUS

Office (OLE) / .XLSX

142.8 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 21712e9cb9833a3d0549cfe58a510d3a SHA-1: 15ad3ce8a77e6645ae53ef4f4aa9a157d14f6cb7 SHA-256: 1ffa8740eef2d512e0f34b42885d319a3ec66172452ccf45c9ad53e4faa11ff6
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. ClamAV identifies the file as 'Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0', strongly suggesting it's an Emotet downloader. The macro's use of dangerous formula APIs like RUN further supports this, indicating it likely downloads and executes a second-stage payload. The document body, a time card, serves as a lure to trick users into opening the malicious macro-enabled file.

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