Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 33b82768a52fcbc9…

MALICIOUS

Office (OLE) / .XLSX

155.2 KB Created: 2022-01-27 11:58:35 Authoring application: Microsoft Excel
MD5: c0f34de9a9b8328e58ed8fe9a8c0d5c5 SHA-1: 3b62cd0e9ecac74c008845f524746cac5e411b8e SHA-256: 33b82768a52fcbc9349a27dbfda1f4eb58ca6ea8a54dbadc0efb84fff0d3ac2f
322 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1218.004 Client Execution

The presence of Excel 4.0 macros, specifically an Auto_Open function, combined with heuristics indicating dangerous formula APIs and a reference to mshta.exe, strongly suggests a downloader. The embedded URLs point to a potential second-stage payload. ClamAV detection as 'Xls.Downloader.Emotet-a5251d1d2d6d3726-9951018-0' further supports the Emotet family attribution and the downloader functionality.

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-a5251d1d2d6d3726-9951018-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-a5251d1d2d6d3726-9951018-0
  • 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://91.240.118.168/zqqw/zaas/fe.htmlB
    • http://91.240.118.168/zqqw/zaas/fe.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e8a01a22c7557f125914eb9c24c0c453abc47445220644b213e0fed4e678b8cf		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3733 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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