Hurwitz & Associates has been running an IT security campaign: “AVID: Anti-Virus Is Dead” for some time. The argument is based on the principle that blacklists of signatures—small files that contain a unique string of bits, or the binary pattern, that identifies all or part of a virus—do not, and cannot, provide adequate protection against viruses. This is because the signature files can only be written once a virus or other form of malicious software program has been identified. When a new malware program is discovered, the race is on to write a signature file for protecting against that virus. It’s like putting a plaster on an open wound, rather than taking care not to get cut in the first place.
Signatures provide ineffective defence against malware such as viruses, unless the exact variant of that malware has been seen before and a specific signature has been made available. Nevertheless, signatures are widely used in security applications. They are used extensively by technology vendors offering intrusion detection and prevention systems (IDSs and IPSs). And they don’t work there, either.
Many also employ heuristics—the application of experienced-derived knowledge based on the way that particular software applications behave. This type of capability is useful since most malicious software applications adhere to some fairly common characteristics. Because of this, they do a better job at catching unknown threats than signatures, but they have the drawback that they can throw up a large proportion of false positives—that is, where a benign application is flagged as malignant.
When hackers try to attack or intrude on a target, they first try to find out as much as they can about that target. They “case the network”, looking to gain as much information about their intended victim as possible: the operating system and applications being used, which versions of software are running, what patches have been applied and so on. Armed with this sort of information, a hacker can plan a more effective attack.
With this in mind, an improved approach is to deploy a perimeter defense system that intercepts penetration testing attacks as they occur, concealing network resources from the hacker and sending back false information. This defense is known as anti-reconnaissance technology.
To quote Sun Tzu, “All warfare is based on deception. Hence, when able to attack, we must seem unable; when using our forces, we must seem inactive; when we are near, we must make the enemy believe we are far away; when far away, we must make him believe we are near.”
Anti-reconnaissance technology takes this principle and applies it to protection of the network. There are only so many reconnaissance tools that can be used to scan a network, such as port scans or BIOS probes, so such probes are relatively easy to identify. Anti-reconnaissance technology works by placing a virtual server in front of the network, intercepting all reconnaissance traffic and responding to attacks on behalf of the network. In this way, the hacker is fed seemingly real data, so they are fooled into believing that the real network is responding, rather than a virtual server that is shielding the network.
Technology vendor Arxceo Corporation, a pioneer in this space, provides anti-reconnaissance appliances that sit in front of network devices, obfuscating the real network and sending responses back to an attacker so that they think they have managed to hit a real network, or dropping attacks into “black holes”. For example, a common exploit used by a hacker is a SYN (synchronization) scan, which is used to determine which ports are open on a network. A hacker does this by sending a SYN packet to every port on the server. If the server sends back a SYN/ACK (synchronization acknowledgment) packet from a particular port, the hacker will believe that the port in question is open and can therefore be attacked. By sending multiple SYN packets to the server, a server can quickly become overwhelmed and a denial of service attack can be achieved.
Arxceo’s appliances work as a virtual pokie machines online server, intercepting all probes made of the network and sending back false data to the source of the probe so that a hacker is provided with misleading information about the network. The Ally appliances are “invisible”, having neither a TCP/IP nor MAC address. Arxceo’s appliances use tagging technology to add information such as IP address and time stamps to the packet returned to the originating source, using IP source authentication techniques to determine the identity of the source. If the source is determined to be authentic, traffic can then be let through to the network.
Even if the source is determined to be authentic and is let through the first anti-reconnaissance engine, Arxceo has a number of other tricks up its sleeve to prevent other exploits from being targeted against a network. It has a second, more advanced anti-reconnaissance engine that can prevent exploits such as stealth scans, where a hacker tries to prevent the request for connexion from being logged. Arxceo’s Ally technology will respond to such an attack by sending back misinformation, hiding what ports are open and addresses in use. Tests indicate that there is zero change of an attacker predicting the sequence numbers for connexion IDs that Arxceo’s Ally imposes.
For more advanced anti-reconnaissance techniques, the technology relies on anomaly and behavior-based protocols for determining whether traffic is good or bad. If a hacker is abusing a certain communications protocol to appear as good traffic, the anomaly-based attack prevention engine will direct the traffic into a black hole. Or where the behavior of the traffic is seen as unacceptable, such as where a hacker is looking for open user datagram protocol ports, or where it does not align with behavioral policies set by the enterprise, it will be stopped by the behavior-based attack prevention engine.
Benefits: the bottom line
The prime benefits of using such anti-reconnaissance technology are not just that it will stop zero day attacks, but that it is “management light”. You won’t even know that the technology is there. The appliances can be plugged into existing networks without the need for network modifications. Since the network cannot be breached, signature and characteristic-based techniques are not needed. The company no longer needs to maintain and constantly update resource-guzzling databases of signatures for all the malware threats that they face.
As the threats that we face grow in both number and complexity, better techniques are required for guarding against them. We need proactive tools that can counter attacks previously not seen, rather than reactive tools based on signatures. It’s time to meet the enemy in the field and turn the enemy’s tactics against them.