CrowdStrike says one AI assisted attacker may be behind the South Korean bank hacks
Last week some of South Korea's biggest banks were hit by a cyberattack. Thanks to a report from CrowdStrike tonight, we now know the entire hack may have been done by a single person. He used a combined stack of an open-source AI penetration tool named ARTEX, DeepSeek v4.1-Flash, GLM-5.3, Grok 4.6, and Claude Code.
Context
It is a documented case of off the shelf AI agents helping what may be a single attacker breach major banks.
Several South Korean financial organizations reported data breaches between late September and early October, according to Korean media reports cited by CrowdStrike. CrowdStrike says the attacker used ARTEX, an open source agentic penetration testing tool developed in China, together with language models run through Claude Code. The firm has not tied the activity to a named group, and the number of affected organizations remains unconfirmed.
Deep dive
CrowdStrike Intelligence published its findings on October 7. It says it found infrastructure tied to a campaign against South Korean financial organizations that ended with stolen data, active from late September to early October 2026. Reports cited in the analysis say the attacker reached a loan progress inquiry service used by brokers at one bank and an employee mobile work support system at another.
The strongest evidence came from the attacker's own servers. CrowdStrike says open directories exposed Claude Code session histories, ARTEX configuration files and Claude memory files, including a CLAUDE.md file holding a Chinese language penetration testing prompt. According to the report, the ARTEX instance used DeepSeek v4.1 Flash as its main model, while GLM 5.3 from Zhipu AI and Grok 4.6 were used in additional Claude Code sessions. DeepSeek was likely reached through an API reseller.
The sessions also show the attacker asking Claude where Korean breach data is usually sold and for help finding Korean Telegram groups that trade it. In one session the user asked for a security researcher resume describing the results, with personal details pointing to a 26 year old in Guangdong, China. CrowdStrike says those details likely belong to the attacker but cannot be definitively linked, so the identity is unconfirmed.
CrowdStrike assesses with moderate confidence that the actor is a Chinese speaker motivated by money. It says the case shows how AI tooling lets one financially motivated actor run several intrusions in a short time.
What to expect next
CrowdStrike expects adversaries to keep adding AI tooling to their operations to raise their tempo. The open questions are how many institutions were hit, what data was taken, and whether Korean authorities confirm who the attacker is.
Watch for statements from the model providers named in the report, for any change in how ARTEX is distributed, and for guidance from Korean regulators to banks on intrusions run with AI agents.