Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 984fd8cc68286a14…

MALICIOUS

Office (OLE) / .XLSX

143.4 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 1a24f3e77ac4e71cd21b20e3f5e35ec4 SHA-1: 7a081ad5de0cf7e616b2e822e7dc6b39ae5ce5e8 SHA-256: 984fd8cc68286a146c035c8bcc0f47c087ca16e50ae2abde9de990ba97e4e2a1
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 macro, which is a known technique for executing malicious code. ClamAV identified the file as 'Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0', strongly suggesting Emotet family involvement. The Auto_Open macro likely initiates the download of a secondary payload, consistent with Emotet's typical 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
46284ea41c691066b9fe85a87bc7e9bfc77336182ea3b4ed700574b0c8cd3189		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3141 bytes

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