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Invest2 publishersAlso reported elsewhere2 min readPublished

One operator used a free pentest agent and Claude Code to breach as many as nine Korean banks

ARTEX's developer made the open-source agent closed-source on October 8 after CrowdStrike linked it to a China-based 26-year-old who breached South Korean banks. The campaign exposed roughly 68,000 customer records, Cryptobriefing reported.

The Investor · Invest desk

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What happened

  • Shinhan Bank was the worst hit, with around 25,000 customer records compromised.
  • The exposed personal data included names, phone numbers, annual incomes and loan limits.
  • ARTEX is not a standalone model but connects to external LLMs such as ChatGPT, Claude and DeepSeek to run its probing.
  • Attack traffic was routed through IP addresses spanning more than ten countries to obscure its origin.
  • ARTEX's GitHub page was taken down the same day the project went closed-source.

Compiled by The InvestorSomething wrong?How this is made

Why it matters

  • cost The leaked data, including annual incomes and loan limits, enables highly targeted financial fraud, and the people whose records were taken carry that risk.
  • constraint The developer's step is prospective: no further versions and no maintenance support. It does nothing about the open-source versions already published this year.
  • exposure Claude Code sat in the attack chain, so whether model providers should keep their assistants out of such chains is now Anthropic's question to answer; the company has not commented.
  • capability A single operator with a downloadable tool and a commercial AI assistant breached multiple banks, which lowers the resources needed to attack a financial institution to within one person's reach.

The tool cost nothing: ARTEX was released on GitHub this year as an open-source agent to automate penetration testing [17]. CrowdStrike said the operator was a single 26-year-old based in China who ran it alongside Anthropic's Claude Code, an account carried by both Cryptobriefing and Mint [9][10][21]. The campaign took roughly two weeks [3].

The breaches reached internal banking systems, not the customer-facing portals that carry the heaviest defenses, because internal systems often assume that anyone already inside belongs there [11].

The two reports do not line up on scale. Cryptobriefing put the number of firms at between seven and nine [3]; Mint, citing disclosures and local media, said at least nine banks have been named as targets since late September, and police opened a probe this week [19]. Shinhan alone accounts for about 37 percent of the 68,000 records exposed [23].

The developer, who uses the GitHub handle Autumn-27 and is named by Cryptobriefing as the Chinese cybersecurity engineer Li Puhua [8], announced the change on the code-hosting platform on Thursday. "Given the misuse of the tool, the ARTEX project will no longer be updated and will be converted to closed source. No further versions will be released to the public nor will maintenance support be provided," the developer said [16]. He said he opposed any illegal use of the software and bore no responsibility for conduct that breaks the law [22], and that ARTEX was built for authorized security testing [7].

President Lee Jae Myung called for stronger cybersecurity measures after the incidents [13]. China's foreign ministry spokesperson Mao Ning said on Thursday that the ministry was not familiar with the case and that China consistently opposes and combats hacking [20].

What to watch

  • Whether Anthropic comments on the ARTEX chain or changes Claude Code's safeguards against being wired into attacks.
  • What Korean police conclude, given routing through more than ten countries complicates cross-border attribution.
  • Whether forks or copies of the already-public ARTEX code resurface despite the switch to closed-source.

Claim ledger

Ranked by verification strength, evidence, and original report placement.

  1. [1]

    ARTEX was converted to a closed-source project on October 8, 2026.

    ReportedView cited source
  2. [2]

    ARTEX's GitHub page was taken down the same day the project went closed-source.

    ReportedView cited source
  3. [3]

    The attacks struck between late September and early October 2026, roughly a two-week span, and breached internal systems at between seven and nine South Korean financial firms.

    ReportedView cited source

Sources

2 independent publishers whose own reporting we read for this story.

  1. cryptobriefing.com

    1 article · October 9, 2026

    ARTEX AI agent goes closed-source after being linked to South Korean bank hacks
  2. economictimes.indiatimes.com

    1 article · October 8, 2026

    ARTEX AI agent: Chinese developer makes ARTEX AI agent closed-source after Korean bank hack - The Economic Times
  3. livemint.com

    1 article · October 8, 2026

    Chinese developer makes ARTEX AI agent closed-source after Korean bank hack | Mint

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