By Dan Holden and Curt Wilson of Arbor’s Security Engineering & Response Team (ASERT)
During the months of September and October we witnessed targeted and very serious DDoS attacks against U.S. based financial institutions. They were very much premeditated, focused, advertised before the fact, and executed to the letter.
In the case of the September 2012 DDoS attack series, many compromised PHP Web applications were used as bots in the attacks. Additionally, many WordPress sites, often using the out-of-date TimThumb plugin, were being compromised around the same time. Joomla and other PHP-based applications were also compromised. Unmaintained sites running out-of-date extensions are easy targets and the attackers took full advantage of this to upload various PHP webshells which were then used to further deploy attack tools. Attackers connect to the compromised webservers hosting the tools directly or through intermediate servers/proxies/scripts and issue attack commands. In the September 2012 attacks there were several PHP based tools used, the most prominent of which was “Brobot” along with two other tools, KamiKaze and AMOS which were used a bit less often. Brobot has also been referred to as “itsoknoproblembro”.
The attack tactics observered were a mix of application layer attacks on HTTP, HTTPS and DNS with volumetric attack traffic on a variety of TCP, UDP, ICMP and other IP protocols. The other obvious and uncommon factor at play was the launch of simultaneous attacks, at high bandwidth, to multiple companies in the same vertical.
On December 10, 2012 the group claiming responsibility for the prior attacks, the Izz ad-Din al-Qassam Cyber Fighters announced “Phase 2 Operation Ababil”. A new wave of attacks were announced on their Pastebin page: which described their targets as follows:
“Continually, the goals under attacks of this week are including: U.S. Bancorp, JPMorgan Chase&co, Bank of America, PNC Financial Services Group, SunTrust Banks, Inc.”
On December 11, 2012, attacks on several of these victims were observed. Some attacks looked similar in construction to Brobot v1, however there is a newly crafted DNS packet attack and a few other attack changes in Brobot v2.
These attacks have shown why DDoS continues to be such a popular and effective attack vector. Yes, DDoS can take the form of very large attacks. In fact, some of this week’s attacks have been as large as 60Gbps. What makes these attacks so significant is not their size, but the fact that the attacks are quite focused, part of an ongoing campaign, and like most DDoS attacks quite public. These attacks utilize multiple targets, from network infrastructure to Web applications.
While there has been much speculation about who is behind these attacks, our focus is less on the who or why, but how we can successfully defend. There are multiple lessons to be learned from these attacks, by everyone involved – the targeted enterprises, their managed security providers, Website and Web application administrators, and the vendor community.
For enterprises, it is clear that typical perimeter defenses such as firewalls and IPS are not effective when dealing with DDoS attacks, as each technology inline to the target is actually a potential bottleneck. These devices can be an important part of a layered defense strategy but they were built for problems far different than today’s complex DDoS threat. Given the complexity of today’s threat landscape, and the nature of application layer attacks, it is increasingly clear that enterprises need better visibility and control over their networks which require a purpose built, on-premise DDoS mitigation solution. This could sound self-serving, however, visibility into a DDoS attack needs to be far better than the first report of your Website or critical business asset going down. Without real-time knowledge of the attack, defense and recovery becomes increasingly difficult.
For providers of managed security services, they have begun to evaluate their deployments and mitigation capacity. These attacks were unique in that they targeted multiple organizations within the same vertical, putting a strain on the capacity of provider’s cloud-based mitigation services.
What these attacks have continued to demonstrate is that DDoS will continue to be a popular and increasingly complex attack vector. DDoS is no longer simply a network issue, but is increasingly a feature or additional aspect of other threats. The motivation of modern attackers can be singular, but the threat landscape continues to become more complex and mixes various threats to increase the likelihood of success. There have certainly been cases where the MSSP was successful at mitigating against an attack but the target Website still went down due to corruption of the underlying application and data. In order to defend networks today, enterprises need to deploy DDoS security in multiple layers, from the perimeter of their network to the provider cloud, and ensure that on-premise equipment can work in harmony with provider networks for effective and robust attack mitigation.