First of all I would like to thank everyone for suggestions.

We actually run quite sensitive traffic on our network and we are curious if
there is a breach or there might be a potential one.There is no suspicious
activity as far as we noticed but there is always a possibility that might
be an unknown or undetectable backdoor on the system.We patch our softwares
with the latest releases regularly but there can be a zero day vulnerability
of course and this can lead to a breach too.

What we actually looking for is a company or person who is specialized on
whole system security to examine our systems for known and
unknown/underground threats.I know talking about %100 security makes no
sense but relatively we think there might be some considerable improvements
if the system is scanned for underground threats as well as known
vulnerabilities.

We have a friend who is providing ethical hacking services and he used to be
a black hat..Do you think it is ok to trust a blackhat ? He is a professinal
but when it comes to a situation that you are only working for a company,
not owning one, decisions are harder to take.Please share your experiences
about hiring a blackhat, if there is any.

Thanks again.
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