Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 ca841fc1b033f53c…

MALICIOUS

Office (OLE) / .XLSX

79.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-18
MD5: 77f18b0b905c1f89e298656de65a5c31 SHA-1: aa7a8443fde26f15f709633d6b5d280e3556ec34 SHA-256: ca841fc1b033f53c0b24b2f7714fe72c4572b162ad580a8c85fb6e88208d3a7a
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: User Execution T1059.001 Command and Scripting Interpreter: PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a critical indicator of malicious intent. The macros are designed to execute dangerous functions, including the RUN API, suggesting a downloader. The reconstructed URLs from the DOC BODY section indicate the likely source of the second-stage payload. ClamAV detection further confirms its classification as Emotet. The script's primary function is to download and execute a payload from one of the provided URLs.

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-ea85857e7e81817a-9950241-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-ea85857e7e81817a-9950241-0
  • 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
9adf99aa959e452d549d1e4979c57edf0d871284640bacfef310bdb0044249bc
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7262 bytes