Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 31d59aabd93bc849…

MALICIOUS

Office (OLE) / .XLS

73.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-18
MD5: ae59d66091fe0865cc0b26ca81b745b1 SHA-1: f6402a93363f8d2994c3a7c255f878b2edcc5fc9 SHA-256: 31d59aabd93bc849e17e002a2eb686832533be088dfd9e96e9bdda05be739f7b
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open function, specifically using the RUN API, which is a strong indicator of malicious intent. The ClamAV detection further confirms this, identifying the file as 'Xls.Downloader.Emotet'. The embedded document body contains concatenated strings that, when reconstructed, form multiple URLs. These URLs are likely used to download and execute a second-stage 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-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
cde40ac8101f526fd4a9300ec8b1668ace4e30df6493fc373c611b3342d60d83		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7173 bytes

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