Cybersecurity researchers took the wraps off a novel supply chain attack in South Korea that abuses legitimate security software and stolen digital certificates to distribute remote administration tools (RATs) on target systems.
Attributing the operation to the Lazarus Group, also known as Hidden Cobra, Slovak internet security company ESET said the state-sponsored threat actor leveraged the mandatory requirement that internet users in the country must install additional security software in order to avail Internet banking and essential government services.
The attack, while limited in scope, exploits WIZVERA VeraPort, which is billed as a "program designed to integrate and manage internet banking-related installation programs," such as digital certificates issued by the banks to individuals and businesses to secure all transactions and process payments.
The development is the latest in a long history of espionage attacks against victims in South Korea, including Operation Troy, DDoS attacks in 2011, and against banking institutions and cryptocurrency exchanges over the last decade.
Aside from using the aforementioned technique of installing security software in order to deliver the malware from a legitimate but compromised website, the attackers used illegally obtained code-signing certificates in order to sign the malware samples, one of which was issued to the US branch of a South Korean security company named Dream Security USA.
"The attackers camouflaged the Lazarus malware samples as legitimate software. These samples have similar file names, icons and resources as legitimate South Korean software," ESET researcher Peter Kálnai said. "It's the combination of compromised websites with WIZVERA VeraPort support and specific VeraPort configuration options that allows attackers to perform this attack."
Stating that the attacks target websites that use VeraPort — which also comes with a base64-encoded XML configuration file containing a list of software to install and their associated download URLs — ESET researchers said the adversaries replaced the software to be delivered to VeraPort users by compromising a legitimate website with malicious binaries that were then signed with illicitly acquired code-signing certificates to deliver the payloads.
"WIZVERA VeraPort configurations contain an option to verify the digital signature of downloaded binaries before they are executed, and in most cases this option is enabled by default," the researchers noted. "However, VeraPort only verifies that the digital signature is valid, without checking to whom it belongs."
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The binary then proceeds to download a malware dropper that extracts two more components — a loader and a downloader — the latter of which is injected into one of the Windows processes ("svchost.exe") by the loader. The final-stage payload fetched by the downloader takes the form of a RAT that comes equipped with commands allowing the malware to perform operations on the victim's filesystem and download and execute auxiliary tools from the attacker's arsenal.
What's more, the campaign appears to be what's a continuation of another Lazarus-mounted attack called Operation BookCodes detailed by the Korea Internet & Security Agency earlier this April, with significant overlaps in TTPs and command-and-control (C2) infrastructure.
"Attackers are particularly interested in supply-chain attacks, because they allow them to covertly deploy malware on many computers at the same time," the researchers concluded.
"Owners of [websites with VeraPort support] could decrease the possibility of such attacks, even if their sites are compromised, by enabling specific options (e.g. by specifying hashes of binaries in the VeraPort configuration)."