Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 81e197d3d6b2000b…

MALICIOUS

Office (OLE) / .XLSX

47.9 KB Created: 2022-01-28 19:27:26 Authoring application: Microsoft Excel
MD5: a96575922c8a9eebd6794412de2a039f SHA-1: 6097e7db94988442ded00d926ad0fe970c12965c SHA-256: 81e197d3d6b2000b28d573dbb1c9f9ac18d3e69a66dc87548b1fac6f463a2ed8
262 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1218.005 System Binary Proxy Execution: Mshta

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a strong indicator of malicious intent. The macro is designed to execute 'mshta http://91.240.118.172/mm/nn/se.html', indicating it downloads and runs a second-stage payload. ClamAV detection as 'Xls.Downloader.Emotet-a5251d3d2d6d3722-9951020-0' further supports the Emotet family attribution.

Heuristics 7

  • 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.
  • ClamAV: Xls.Downloader.Emotet-a5251d3d2d6d3722-9951020-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-a5251d3d2d6d3722-9951020-0
  • Reference to mshta.exe high SC_STR_MSHTA
    Reference to mshta.exe
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://91.240.118.172/mm/nn/se.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
2a39d235e725445537a5ed24b54fc0fe8d7c72d89b68b4fdcce55aba466e47aa		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3184 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 shell/COM execution token(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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