Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 687bc4b590ab8578…

MALICIOUS

Office (OLE) / .XLS

232.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-25
MD5: 6fe4c5bbed08ab8f8f96029ab47e079c SHA-1: 1bae1ee39d05247fc2586f0accf6b674fcbf277b SHA-256: 687bc4b590ab8578f6a7d7de9958ad559faf8786c34ef709dbd071f19a46f3cb
282 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file contains Excel 4.0 macros with an Auto_Open entry, which is a critical finding. These macros are designed to download and execute a second-stage payload from a list of six embedded URLs. The ClamAV detection explicitly names this as 'Xls.Downloader.Emotet', strongly suggesting the Emotet family. The macros also attempt to use regsvr32.exe, indicating execution of downloaded content.

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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