ARTEX disappeared from GitHub on 8 October, a day after researchers connected it to a run of data thefts at South Korean banks. Its developer, who publishes under the handle Autumn-27, wrote that the project "will no longer be updated and will be converted to closed source", with no further public versions and no maintenance support.
The tool describes itself as an autonomous penetration system built on several AI agents working together. Released on 26 July 2026 under an open licence, it split the work between agents with distinct roles: one breaking a goal into steps, one planning and several executing. A person could approve or halt any action they took, which puts it in the class of software built to act rather than advise.
CrowdStrike put it at the centre of the Korean attacks in a post on 7 October. Researcher Ashley Campion wrote that the actor is likely a Chinese speaker and financially motivated, an assessment made with moderate confidence and attributed to no named adversary.
Researchers got their view through open directories the attacker had left exposed on two servers. One held a Chinese-language hacking prompt in a Claude Code file, and the other, in Hong Kong, exposed the operator's saved chat logs, ARTEX configuration files and the notes the agents kept between runs. Those showed DeepSeek, Zhipu and Grok models running alongside each other.
The same logs recorded the operator asking Claude where stolen Korean data is usually sold, and for help finding Korean data-trading groups on Telegram. Researchers found no indication the models refused.
How The Attackers Got In
At Shinhan Bank the entry point was a loan-progress lookup service built for outside brokers rather than staff, and attackers fed random customer numbers into it for about 30 hours from 28 September. None of that has much to do with AI.
Guessing identifiers until valid ones appear is a technique older than most of the banks' systems, and capping how many attempts a service accepts is the standard answer to it. How a mobile-phone verification step was bypassed has not been explained.
KB Kookmin's breach came through an employee mobile work-support system, and BNK Busan found data exposed on web pages with what it called insufficient session validation. None of the attacks touched the hardened core banking systems.
An official at South Korea's Financial Security Institute put the limit on the AI framing plainly, saying the software "did not act independently without human involvement". The same official noted that a great many open-source AI tools like ARTEX exist.
The Records That Went Missing
Counts differ across Korean outlets, and no regulator has published a final figure. Yegaram Savings Bank appears worst affected with around 40,000 records, followed by Shinhan at about 25,700, Welcome Savings Bank at roughly 2,200 corporate records, Hyundai Capital at 146 and Hana Bank at 89.
KB Kookmin's figure is reported as either 119 or 153, with one account breaking the lower number into 99 customers and 20 current and former employees. Totals across the sector run between 66,000 and 70,000 records depending on the outlet, and the number of firms affected is given as five, seven or nine.
Names, phone numbers, addresses, annual income, loan limits and encrypted resident registration numbers, South Korea's national identity numbers, appear in the disclosures. Regulators confirmed no passwords, one-time codes or customer funds were taken.
Korean police have linked 28 internet addresses to the attacks, most believed to be relays hiding the real origin. Because anyone could download ARTEX while it was public, nationality cannot be inferred from the tool alone.
A Résumé In The Logs
In one session the operator asked Claude for help writing a security researcher's résumé describing the attack results. Into it went a Telegram handle, a first name, a city in Guangdong province and a university.
The same prompt gave an age of 26 alongside a birth date in September 2007, which would make the person 19. CrowdStrike says the available information cannot definitively associate those details with the attacker.
Reuters reported the suspect as a China-based 26-year-old, a firmer formulation than CrowdStrike published. The Chinese foreign ministry said it was not familiar with the case and that China opposes hacking.
Seoul Is Changing The Rules
South Korea's Financial Services Commission called an emergency meeting on 4 October, a public holiday, summoning the chief executives of Hana, KB Kookmin and Shinhan. Inspectors went into Shinhan and later KB Kookmin.
Firms were told to block external access to systems unless essential, and to limit how much credit data outside personnel such as loan brokers can see. They were also told to verify that around 30 attacker addresses were blocked, and to complete an emergency security review by 8 October.
Lee Eok-won, who chairs the commission, was blunt at a parliamentary audit. "Even in some very basic areas, our response has been inadequate," he said, adding that "to prevent attacks using AI, we ultimately have no choice but to use AI in defending them."
Shinhan's 2026 information security budget was 40.59bn won, about $30.2M, the lowest among the four big commercial banks, against KB Kookmin's 86.07bn won. Regulators say spending alone does not explain the differences in damage.
A Withdrawal That Retrieves Nothing
ARTEX went out under a licence that lets anyone copy and republish the code, so closing the original did not recall what had already been taken. A translated copy built from that code was still online after the developer withdrew the project.
The models sped up the groundwork and the search for buyers, handing a single person the output of a team. The systems that gave way in Seoul, though, did so for reasons that predate every tool named in the case.
