Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 e2cb3171d33922af…

MALICIOUS

Office (OLE) / .XLSX

126.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-28
MD5: 847ee64d38eb365788c9ff7eb7d3798a SHA-1: 9d2292da73b1f2bec26b2bd18cea11c616898505 SHA-256: e2cb3171d33922afd8aa4a93cae06041f248913551f4195671cf5123b6b7b1a7
262 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1204.002 Malicious File Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros with an Auto_Open entry, which is a critical finding. The macros reconstruct and utilize multiple URLs to download a second-stage payload, as indicated by the 'Xls.Downloader.Emotet' ClamAV detection. The script also explicitly calls 'regsvr32.exe' with reconstructed URLs, suggesting it's used to download and execute malicious content. The reconstructed URLs are: "h"&"tt"&"p://med.devsrm.com/wp-content/gtOOTHi3zkUbn8U6/", "h"&"tt"&"p://izytalab.com/includes/1mafAX0kOa/", "h"&"tt"&"ps://pcsolutionss.com/zSlT4HR92TiOpw5NM/", "h"&"tt"&"p://www.doctorcasenave.com/wp-content/O2Z1HMebIXiHYBBS/", "h"&"ttp"&"s://wpl28.realtyna.com/wp-content/0b0ny5cPM/", and "h"&"tt"&"p://www.efcballjoint.com/Template/AxEZPOfAa9/".

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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