Malware creators are constantly developing new techniques to circumvent traditional anti-virus defenses and ensure their malicious code can run undetected on a targeted machine.

Zero-day malware variants, those which have never been seen before, are not picked up by signature-based AV solutions. However, the malware will need to communicate with its owner, so the source code will contain URLs and IPs for that purpose. These URLs can be detected when scanning files. If the URLS are detected and they are known to be malicious, the file will be deemed to be malicious and will be quarantined.

To ensure this does not happen, malware developers use a variety of techniques to hide the URLs and IPs in the source code. This is often achieved by converting the IP address into a decimal value, which is stored as XML content. When in decimal format, even a malicious URL would not be detected as such by most antivirus software. When the IP address is needed by the malware, it can be converted back to its original form and then reconverted to digital when no longer required.

Similarly, a URL – or part of a URL – could be encoded in its hexadecimal equivalent. That URL would be unlikely to be detected as malicious yet can be read by a browser. AV software would likely detect the file example.com/maliciousfile.exe as malicious in nature and would block it accordingly. In hexadecimal, that translates to:

%65%78%61%6D%70%6C%65%2E%63%6F%6D%2F%6D%61%6C%69%63%69%6F%75%73%66%69%6C%65%2E%65%78%65

That address would not be recognizable as malicious and would likely go undetected during a scan by an AV solution. The use of both obfuscation techniques together is not unusual, to make it even harder for AV solutions to detect malicious URLs and IPs.

While these techniques can be used to fool endpoint AV solutions, connections to those malicious servers can be blocked using a DNS-based content filter such as WebTitan.

It doesn’t matter how the URL or IP address is masked. Before a connection can be made, it is necessary to make a DNS query, and the collection must be permitted by the DNS-based filter. If the URL is malicious, the DNS filter will block the attempt to connect before any content is downloaded.

WebTitan works in conjunction with a real time database of millions of malicious URLS and uses a real-time classification system to assign websites to one of 53 categories. Those categories can be allowed or blocked with the click of a mouse. In addition to blocking access to malicious content, the category-based controls can be used to prevent employees from accessing content that could cause offense or lower productivity.

To find out more about how WebTitan can benefit your organization and improve your security posture, contact the TitanHQ team today.