If you are using Mac OS X 10.9, that is actually not a malware or adware issue. This problem is, unfortunately, normal with Mac OS X 10.9.
Recently, 10.9 systems began to have problems verifying certificates for certain sites. The bluekai.com sites, as well as the Oracle site (who owns bluekai.com), are among the affected sites. I've also seen recent reports of the problem with adnxs.com.
I am not clear at this point what the cause of the problem is, but I have been able to confirm this behavior on a freshly-installed, clean 10.9 system.
Unfortunately, there are only two options available to you. One is to upgrade or downgrade your system. Mac OS X 10.10 and higher do not suffer from this problem, and strangely, for whatever reason, Mac OS X 10.8 is also not affected.
The other option is to stop using Safari and switch to Chrome or Firefox.