Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 17c7abf47c94a7bb…

MALICIOUS

Office (OLE) / .XLSX

126.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-29
MD5: 469f11be60d31a7f7d4a5f35297b7e98 SHA-1: cca46c498205ebef2d867b9e73416fb8f8f3aa89 SHA-256: 17c7abf47c94a7bbfde7d2df3845469863f2f984cb831bcdfe8ca1673848e86b
262 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros with an Auto_Open entry, indicating automatic execution upon opening. These macros reconstruct and utilize multiple URLs to download and execute a second-stage payload, as indicated by the ClamAV detection for Emotet. The use of regsvr32.exe is also present in the macro logic, suggesting execution of downloaded components.

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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