Earlier this month, a security researcher found that Polish banks had been infected by malware that was triggering out-of-bounds network traffic. Upon further investigation, researchers from BadCyber discovered that the attackers originally targeted the Polish Financial Supervision Authority website, which then infected other systems connected to it, including as many as 20 other banks.

Once this malware was injected to the workstations by the infected server, the researchers noted, it could then “perform network reconnaissance, lateral movement and data exfiltration.” In some cases it even enabled attackers to control key servers within bank infrastructure.

Moving Beyond Polish Banks

Symantec and BAE Systems investigated the attack and drew some troubling conclusions. First, as BAE researchers noted on their Threat Research Blog, the attack’s custom exploit kit was set up to infect only visitors with certain IP addresses.

Furthermore, the malware used a Silverlight-based exploit to carry out the infection process. This technical process is linked to the Lazarus Group, a notorious gang of threat actors.

SecurityWeek reported that cybercriminals used this custom exploit kit to target Symantec customers located in Poland, Mexico and Uruguay. These attacks were first identified in October 2016.

BAE Systems also found evidence that the website of a state-owned bank in Uruguay underwent a similar Lazarus-inspired attack. Tellingly, one of the domains used in the Poland attack had also been used in a campaign against the National Banking and Stock Commission of Mexico, suggesting that all the attacks are connected.

Lazarus Lives

The Lazarus Group has been a potent threat actor in the past. Best known to the public for its 2014 attack against Sony, SecurityWeek estimated that the group may have originated in early 2007. In the past, it focused on government, military, media, aerospace, financial and manufacturing organizations located primarily in South Korea and the U.S.

SecurityWeek further noted that this type of financial attack would fit into Lazarus’s method of operations, since it was linked to the massive breach that cost the Bangladesh Central Bank $81 million last year.

Lazarus is out there and shooting arrows, but it’s no Cupid. These arrows aim for big payoffs, and IT leaders must develop strategies to keep up with what has proven to be a wily and competent adversary.