Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 f9c8a6a9e7eb0b9b…

MALICIOUS

Office (OLE) / .XLSX

56.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-27
MD5: fa8b613de10e2cb51dc5ed2b7310953e SHA-1: d09c57ab276913e6feac878b197c8450f9352ddc SHA-256: f9c8a6a9e7eb0b9bc398bfde93ee745c35d9e69307041d9acd8c9c8ac5bb0dca
262 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro that utilizes dangerous functions like RUN. The macros reconstruct and attempt to download payloads from multiple URLs, including "http://clipacc.com/img/doXw68d7bqxxhwuxNb0N/". The ClamAV detection and the nature of the macros strongly indicate Emotet, a known downloader family. The script also references 'regsvr32.exe', suggesting it may be used to execute downloaded payloads.

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: Doc.Downloader.Emotet03220-9942564-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Emotet03220-9942564-0
  • 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://clipacc.com/img/doXw68d7bqxxhwuxNb0N/
    • http://chadhymas.com/wp-admin/yo11rETlmzRqZlC56B/
    • http://mulmatdol.com/adm/YO7lpLlRnPIM/
    • http://fmesperanza945.com/fonts/Mta/
    • http://clanwatson.co.uk/personal/DxlCbK5yxbqq1jqP/
    • https://classicpaint.net/wp-content/Vx6iP4KOyoZuiwsyW/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
5834970f734bf661b309120f05c0862d1e7420175d65222097e2d0e18d98d2e0		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6614 bytes

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