Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 de194184575783e1…

MALICIOUS

Office (OLE) / .XLSX

106.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-29
MD5: d6e2b10ded4007917f6b99c09ec1eaf2 SHA-1: 8e3da6244ba89d6a847c438ce97d534317dc2bed SHA-256: de194184575783e158c569cdb62687aa7e8fbb8472461511e2626db0430fadea
262 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros with an Auto_Open entry, which is a critical finding. The macros reconstruct and utilize multiple URLs to download and execute a payload, indicated by the 'regsvr32.exe' and '..\hdrh.dll' artifacts. ClamAV detection further confirms its malicious nature, identifying it as Emotet. The reconstructed URLs are the primary indicators of compromise for the initial download stage.

Heuristics 6

  • 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.
  • URL reconstructed from XLM cell array (6 URLs) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • ClamAV: Xls.Downloader.Emotet-b2cbc93e36c0c13e-9950560-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b2cbc93e36c0c13e-9950560-0
  • 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.
  • 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://dougveeder.com/cgi-bin/xJ91ZttGRioQ7IUL/
    • https://e-fistik.com/ajax/PnA23/
    • http://dsinformaticos.com/_private/f36Yl/
    • http://dstny.net/cgi-bin/POqJKcxiIzRb/
    • http://fakecity.net/cache/XtIzhyLEoLI7/
    • http://fayeschmidt.com/cgi-bin/Q8pj6/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
42fcced62e1b0500e019d401d9861bc8ead898ce0c99e4725ba96347a4a0e47e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6551 bytes

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