Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 c3aa622ce21dba28…

MALICIOUS

Office (OLE) / .XLS

126.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-29
MD5: 32da10c5ece451007313e1c9dbe1e943 SHA-1: f7c5662ebe0bfc7a1e175185348b47652afd5470 SHA-256: c3aa622ce21dba28eaff3645ae335b4645030f415f8d9bc4bbdd1c47548c78a6
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

The file is an Excel 4.0 macro-enabled workbook that leverages an Auto_Open macro to execute. The macro reconstructs and calls URLs to download a second-stage payload. The ClamAV detection and the nature of the macro execution strongly indicate the Emotet family. The macro uses string concatenation to build URLs, such as "http://drvishalchestclinic.com/wp-includes/SqqCZQ6y2uyFF/". It also calls regsvr32.exe, likely to execute the downloaded payload.

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-adc2d23d2dc26dd0-9950240-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-adc2d23d2dc26dd0-9950240-0
  • 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://drvishalchestclinic.com/wp-includes/SqqCZQ6y2uyFF/
    • http://funestotal.com/5aclo1em/21U/
    • http://g-wizcomputers.com/party/61W0ovBu86/
    • http://primefind.com/1mall-uk/h5/
    • http://la-csi.com/mt-admin/BB7/
    • https://pancook.com/newsite/H6xxeLefX1I2vgJFM1Y/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
baa385ee141091e506d4fc8952e60f349e2a144300202c59dbc3e03ea3f9b493		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6541 bytes

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