Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 6eb16e0690e24c1b…

MALICIOUS

Office (OLE) / .XLSX

106.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-29
MD5: 0834fc1bdfa7726ad23eae86316d6d04 SHA-1: 15d428648ea8f8986ad3b455e60e2f9c05a63ed1 SHA-256: 6eb16e0690e24c1b65d09c39133e26dee115930191fbb0b6a2a6bbf2963962c1
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, specifically an Auto_Open entry, which is a critical indicator of malicious intent. These macros are designed to execute dangerous API functions, including constructing and downloading payloads from multiple hardcoded URLs. The ClamAV detection and the presence of these URLs strongly suggest this is a downloader for the Emotet family.

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-b2cbc93e36c0c13e-9950560-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b2cbc93e36c0c13e-9950560-0
  • 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://dougveeder.com/cgi-bin/xJ91ZttGRioQ7IUL/
    • https://e-fistik.com/ajax/PnA23/
    • http://dsinformaticos.com/_private/f36Yl/
    • http://dstny.net/cgi-bin/POqJKcxiIzRb/
    • http://fakecity.net/cache/XtIzhyLEoLI7/
    • http://fayeschmidt.com/cgi-bin/Q8pj6/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
42fcced62e1b0500e019d401d9861bc8ead898ce0c99e4725ba96347a4a0e47e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6551 bytes

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