Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 2fa81cafabdb4429…

MALICIOUS

Office (OLE) / .XLS

232.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-25
MD5: da31cfa407d4ebc1dea801a994d9b600 SHA-1: 7b3541c88d98589c053a648c1fe2e6e11dd56958 SHA-256: 2fa81cafabdb44292dacce6c3c67acc2c5d74d18d8c50a137e2eefcb46aa9a72
282 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1059.003 Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. These macros are designed to download a payload from one of the six embedded URLs. The ClamAV detection explicitly names this as 'Xls.Downloader.Emotet', strongly indicating the Emotet family. The reconstructed URLs are the primary indicators of compromise.

Heuristics 7

  • 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-b600c9ff3ec1c136-9950239-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b600c9ff3ec1c136-9950239-0
  • 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.
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code
  • 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://contrid.com/6vwkQmRU/
    • http://ctfilms.com/ks/2ygJuGV0/
    • http://cordclipsorganizer.com/cable-holder-2e/a/
    • http://dahiaka.com/DND/JuBlOiT8Ixj/
    • https://www.colfincas.com/tmp/FvyLs/
    • http://contentunion.net/newwebsite/UXkkk/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
9782ec94f612fa6014316c57f3aba31c20f5ca1075c2c12ef31787a22df00283		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7009 bytes
macros.bas
aaa8e4140b1a48ed914365038bfd1f4385374eef9f5c42b5b515efeb43137002		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 1781 bytes

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