After more than four years of investigation, the Public Prosecutor’s Office Verden and the Lüneburg Police in cooperation with the US Attorney’s Office for the Western District of Pennsylvania, the DOJ and the FBI, Europol and Eurojust, dismantled an international criminal infrastructure platform known as Avalanche.
The Avalanche network was used as a delivery platform to launch and manage mass global malware attacks and money mule recruiting campaigns. It has caused an estimated EUR 6 million in damages in concentrated cyberattacks on online banking systems in Germany alone.
The monetary losses associated with malware attacks conducted over the Avalanche network are estimated to be in the hundreds of millions of euros worldwide, although exact calculations are difficult due to the high number of malware families managed through the platform.
The global effort to take down this network involved the crucial support of prosecutors and investigators from 30 countries. As a result, 5 individuals were arrested, 37 premises were searched, and 39 servers were seized. Victims of malware infections were identified in over 180 countries. Also, 221 servers were put offline through abuse notifications sent to the hosting providers.
The operation marks the largest-ever use of sinkholing to combat botnet infrastructures and is unprecedented in its scale, with over 800,000 domains seized, sinkholed or blocked.
“Avalanche shows that we can only be successful in combating cybercrime when we work closely together, across sectors and across borders. Cybersecurity and law enforcement authorities need to work hand in hand with the private sector to tackle continuously evolving criminal methods. The EU helps by ensuring that the right legal frameworks are in place to enable such cooperation on a daily basis,” said Julian King, European Commissioner for the Security Union.
The criminal groups have been using the Avalanche infrastructure since 2009 for conducting malware, phishing and spam activities. They sent more than 1 million e-mails with damaging attachments or links every week to unsuspecting victims.
The investigations commenced in 2012 in Germany, after an encryption ransomware (the so-called Windows Encryption Trojan), infected a substantial number of computer systems, blocking users’ access. Millions of private and business computer systems were also infected with malware, enabling the criminals operating the network to harvest bank and e-mail passwords.
With this information, the criminals were able to perform bank transfers from the victims’ accounts. The proceeds were then redirected to the criminals through a similar double fast flux infrastructure, which was specifically created to secure the proceeds of the criminal activity.
The loss of some of the network’s components was avoided with the help of its sophisticated infrastructure, by redistributing the tasks of disrupted components to still-active computer servers. The Avalanche network was estimated to involve as many as 500,000 infected computers worldwide on a daily basis.
What made the ’Avalanche’ infrastructure special was the use of the so-called double fast flux technique. The complex setup of the Avalanche network was popular amongst cybercriminals, because of the double fast flux technique offering enhanced resilience to takedowns and law enforcement action.
Malware campaigns that were distributed through this network include around 20 different malware families such as goznym, marcher, matsnu, urlzone, xswkit, and pandabanker. The money mule schemes operating over Avalanche involved highly organised networks of “mules” that purchased goods with stolen funds, enabling cyber-criminals to launder the money they acquired through the malware attacks or other illegal means.
In preparation for this joint action, the German Federal Office for Information Security (BSI) and the Fraunhofer-Institut für Kommunikation, Informationsverarbeitung und Ergonomie (FKIE) analysed over 130 TB of captured data and identified the server structure of the botnet, allowing for the shut-down of thousands of servers and, effectively, the collapse of the entire criminal network.