Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 5a3f60b3848d0e9d…

MALICIOUS

Office (OLE) / .XLSX

126.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-28
MD5: 04ea0dd9343c084fbcb506c3bf1b1d8d SHA-1: 2d87159cdf746a1aada4113f750f891b6ad8c267 SHA-256: 5a3f60b3848d0e9d950afc52b6a9261735858762375cc4a0f79ff6065121ad1c
262 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros that are configured to automatically execute upon opening. These macros reconstruct and attempt to download payloads from multiple URLs, including "http://med.devsrm.com/wp-content/gtOOTHi3zkUbn8U6/". The presence of the 'Xls.Downloader.Emotet' ClamAV signature strongly suggests this is an Emotet downloader variant.

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://med.devsrm.com/wp-content/gtOOTHi3zkUbn8U6/
    • http://izytalab.com/includes/1mafAX0kOa/
    • https://pcsolutionss.com/zSlT4HR92TiOpw5NM/
    • http://www.doctorcasenave.com/wp-content/O2Z1HMebIXiHYBBS/
    • https://wpl28.realtyna.com/wp-content/0b0ny5cPM/
    • http://www.efcballjoint.com/Template/AxEZPOfAa9/

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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