Eastern European hackers may only have had access to GozNym banking malware for a few days, but they have already used the malicious software to make fraudulent bank transfers from more than two dozen bank accounts. The new malware is primarily being used to target banks and credit unions, although the attackers have also used the malware to attack e-commerce platforms. 22 attacks have been conducted on financial institutions in the United States with a further 2 attacks in Canada. So far the attackers behind the GozNym banking malware have managed to steal at least $4 million from U.S and Canadian banks.
GozNym Banking Malware Combines Gozi ISFB with Nymaim Source Code
As the name suggests, GozNym banking malware was developed by combining two different malware strains – Nymaim and Gozi ISFB.
IBMs X-Force Research team believe the new malware is the work of the team behind Nymaim malware, as the source code of Nymaim is understood to be only held by the original developers of the malware. The source code for Gozi ISFB malware has previously been leaked on two occasions. X-Force analysts think the Nymaim malware developers obtained that source code and used the best parts to form the new hybrid Trojan.
Nymaim malware has previously been used almost exclusively as a method of ransomware delivery, although the group behind the malware started using it as a banking Trojan late last year. Nymaim malware is a two stage malware dropper that is loaded onto computers using an exploit kit.
Links to a website containing the Blackhole Exploit Kit are sent via spam email. Once Nymaim has been loaded onto a computer, the second payload is deployed. In the case of GozNym banking malware the second stage is the running of Gozi ISFB code.
GozNym banking malware is stealthy and persistent. The malware remains dormant on a computer until the user logs into their bank account. When account details are entered, GozNym records the login credentials and silently sends them to the attackers’ command and control server. If GozNym banking malware is installed, the user will be unaware that their banking sessions have been compromised.
IBM recommends using adaptive malware detection solutions to reduce the risk of an attack. Anti-spam solutions such as SpamTitan can prevent emails containing the malicious links from being delivered, while WebTItan web filtering solutions can be used to block websites containing malicious code and exploit kits.
With new malware constantly being developed – around 1,000,000 new malware samples are now being released every day according to Symantec – organizations now need to implement sophisticated multi-layered defenses to protect their networks from malware infections.