Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 8948fdb1c6ac9b7d…

MALICIOUS

Office (OLE) / .XLSX

106.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-29
MD5: eb1e01a1acbe5680ea02fe47c2a87a7b SHA-1: 7695e77e6ce67ef356c0f891d37c67cd8cbd2a6a SHA-256: 8948fdb1c6ac9b7dafba77634cc24dd3334e8c817b9feb02e03db8c4b08e7996
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, including an Auto_Open entry, which is a strong indicator of malicious intent. These macros are designed to reconstruct and download payloads from multiple URLs, such as "http://fccatinsaat.com/wp-content/Cw3aR6792f/". The ClamAV detection and the presence of regsvr32.exe and a DLL path suggest the execution of a downloaded second-stage payload.

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), across individual numeric cells (one ASCII charcode per cell), or split across multi-char fragment cells a download formula concatenates by reference (=A1&A2&… / CONCATENATE(...)). 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, LABELSST/RK/NUMBER cells, and FORMULA cell-reference concatenation in token order.
  • 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://fccatinsaat.com/wp-content/Cw3aR6792f/
    • http://fabulouswebdesign.net/invoice/m/
    • http://freemanylaluz.com/downloads/8dR9pgNBFtz/
    • https://freewebsitedirectory.com/wp-includes/v2qFAlMZELRkxbz/
    • http://futaba.youchien.net/wp-content/sSJqJ/
    • http://dominionai.org/wp-includes/T5qXAR8p5/

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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