Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 61130c9fd8a6e60f…

MALICIOUS

Office (OLE) / .XLSX

95.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-07-11
MD5: 226ef5c70609dec3ee0a47421b1183db SHA-1: 227171c4deeeb4ed25c6c9f0d51b46bf66f3d45e SHA-256: 61130c9fd8a6e60f204fb7f3725de32365308f5864432c415d5f85d232081f41
200 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is identified as malicious by ClamAV with the signature Xls.Downloader.Emotet. Static analysis revealed the presence of Excel 4.0 macros, specifically an Auto_Open entry that utilizes dangerous formula APIs like RUN. This indicates the macro is intended to execute automatically and likely download a second-stage payload, consistent with Emotet's behavior.

Heuristics 4

  • 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.
  • ClamAV: Xls.Downloader.Emotet-ea81817e7f807ab1-9952142-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-ea81817e7f807ab1-9952142-0
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
85773188e79d904ef8ecf815a27f3a8200cc87e1822ab4901cc9bed29c53e636		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8156 bytes

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