# Daishin Securities Leaks Information of 38,490 People… Account Numbers Also Exposed

> URL: https://www.cityhorror.wiki/en/%EB%8C%80%EC%8B%A0%EC%A6%9D%EA%B6%8C-3%EB%A7%8C8490%EB%AA%85-%EC%A0%95%EB%B3%B4-%EC%9C%A0%EC%B6%9C%EA%B3%84%EC%A2%8C%EB%B2%88%ED%98%B8%EB%8F%84-%ED%84%B8%EB%A0%B8%EB%8B%A4
> Estimated date: Oct 2026
> Last updated: 2026-10-28
> Korean original: https://www.cityhorror.wiki/%EB%8C%80%EC%8B%A0%EC%A6%9D%EA%B6%8C-3%EB%A7%8C8490%EB%AA%85-%EC%A0%95%EB%B3%B4-%EC%9C%A0%EC%B6%9C%EA%B3%84%EC%A2%8C%EB%B2%88%ED%98%B8%EB%8F%84-%ED%84%B8%EB%A0%B8%EB%8B%A4

## Overview

On October 28, 2026, Daishin Securities announced that it had confirmed the theft of personal and credit information belonging to 38,490 customers in a hacking incident. The affected system was a server linked to the opening of non-face-to-face discretionary investment accounts. The incident came to light on October 17, when signs of abnormal hacker access were detected on the server. The eight types of exposed information were customers’ names, email addresses, physical addresses, telecommunications IDs, bank names, deposit and withdrawal account numbers, Daishin Securities comprehensive account numbers, and mobile phone numbers.

Daishin Securities said that the deposit and withdrawal account numbers, comprehensive account numbers, and mobile phone numbers were encrypted, and that it had found no signs of secondary harm or unauthorized access to its core business systems. However, hacking incidents were also confirmed around the same time at Mirae Asset Life Insurance, Mirae Asset Global Investments, and Bithumb, bringing the incident into the spotlight as part of a broader financial-sector security problem. The Financial Supervisory Service (FSS) dispatched on-site inspection teams to Daishin Securities and Bithumb.

## Detection of Suspicious Access and Emergency Response

On October 17, Daishin Securities detected signs of abnormal hacker access to a server linked to the opening of non-face-to-face discretionary investment accounts. Immediately after detecting the suspicious access, it blocked the IP addresses used in the attack and those used to bypass security measures, reported the incident to the relevant authorities, and conducted a detailed investigation into the scope of the breach with the Financial Security Institute.

The investigation continued for about ten days. Daishin Securities examined more than 60,000 signals disguised as legitimate service requests and confirmed that information belonging to 38,490 customers had been exposed, as of October 26.

## Confirmation and Disclosure of the Breach

Daishin Securities disclosed the breach in a press release on the morning of October 28. There were eight types of exposed information in total. The company said that the deposit and withdrawal account numbers, comprehensive account numbers, and mobile phone numbers among them had been encrypted. A company representative said that, to date, no signs of secondary harm or unauthorized hacker access to core business systems had been found.

Daishin Securities said it would individually notify affected customers of the information that had been exposed and respond promptly if any harm was confirmed. To prevent a recurrence, it plans to strengthen access controls and anomaly detection and blocking systems for the server, as well as security checks for external linked systems. The company also plans to compensate customers who suffer losses in accordance with applicable laws and procedures. CEO Jin Seung-wook said, “We take this breach very seriously and deeply apologize to our customers,” adding, “We will responsibly implement the measures necessary to protect our customers and prevent a recurrence.”

## Hacking Incidents Spread Across the Financial Sector

Daishin Securities was not the only company affected. Hacking incidents were also confirmed at Mirae Asset Global Investments and the cryptocurrency exchange Bithumb on the same day. Earlier, on October 26, a customer information breach was confirmed at Mirae Asset Life Insurance, prompting the FSS to conduct an on-site inspection. Yonhap News noted that, with the possible exception of credit card companies, the incident meant that breaches had been confirmed across all major financial sectors following recent hacking attacks.

Bithumb confirmed that an unauthorized outsider had made abnormal access to its internal mobile groupware system and reported the incident to the Korea Internet & Security Agency (KISA) and the Personal Information Protection Commission. So far, only employee information is known to have been exposed, but Bithumb is still investigating the scope of the incident, including the possibility that general user information may have been involved. Bithumb said its internal systems are separate from the virtual asset trading network and that customer assets could not be accessed. Mirae Asset Global Investments detected signs of abnormal access from an external IP address to some of its web systems, blocked the access route, and activated its emergency response system. According to Yonhap News, the company said it had determined that no unique identification information, sensitive information, or personal credit information had been exposed, and that investor information was not involved because the affected systems did not provide services to individual customers.

## Inspections and Warnings from the Authorities

As the incidents mounted, financial authorities took action. The FSS dispatched on-site inspection teams to Daishin Securities and Bithumb to review the circumstances of the breaches. It plans to switch to formal inspections if any legal violations are found. At a meeting with the chairs of bank holding company boards, FSS Governor Lee Chan-jin said, “As artificial intelligence (AI) is used as a hacking tool, security vulnerabilities will be detected more easily and simultaneous attacks will become commonplace,” urging boards to take the lead in improving their IT security capabilities.

The government also began inspections. The Ministry of Science and ICT decided to inspect vulnerabilities at around 172 facilities managed by 111 organizations responsible for major private-sector information and communications infrastructure. It plans to focus in particular on the management of servers and webpages exposed to the external internet. The Korea Economic Daily reported that the measure was prompted by the possibility that assets companies had failed to properly identify or manage were exploited as entry points in recent financial-sector incidents.

## Authenticity Debate

The breach can be viewed either as “an incident whose impact was limited thanks to encryption” or as “a serious security breach in which a server linked to customer accounts was compromised.”

### The View That the Impact Was Limited

According to Daishin Securities, the deposit and withdrawal account numbers, comprehensive account numbers, and mobile phone numbers were encrypted. The company said there were no signs of secondary harm and no unauthorized access to its core business systems. The compromised system was a server linked to account openings. The company blocked the IP addresses used in the attack and those used to bypass security measures immediately after detecting suspicious activity, then examined more than 60,000 signals to determine the scale of the breach. It also said it would compensate customers who suffered losses in accordance with applicable laws and procedures.

### The View That the Incident Was Serious

The opposing view first questions the types of information exposed. Of the exposed information listed by Daishin Securities, only three types were said to be encrypted; the company made no such statement about customers’ names, email addresses, physical addresses, telecommunications IDs, or bank names. Moreover, the statement that “there are no signs of secondary harm” is the company’s own account that no such harm has been identified so far.

The timeline is also a concern. The suspicious activity was detected on October 17, but the breach was confirmed on October 26 and disclosed on October 28. The Korea Economic Daily reported that incidents at Mirae Asset Global Investments and Bithumb had also put the overall security management systems of the financial investment industry under scrutiny. FSS Governor Lee Chan-jin also warned that simultaneous attacks using AI would become commonplace.

## Trivia

- The Korea Ilbo described the scale of the breach as “38,490 cases,” while Yonhap News and Sidae described it as affecting “38,490 people.” Daishin Securities said that information belonging to 38,490 customers had been exposed.
- At a meeting on the morning of October 28, FSS Governor Lee Chan-jin said, “I understand that a major hacking incident affecting financial investment firms in general occurred yesterday.” Daishin Securities disclosed the breach on the morning of the same day.

## Sources

- The Korea Ilbo, [“Daishin Securities leaks over 38,000 records of personal information… Mirae Asset Global Investments and Bithumb also breached”](https://www.hankookilbo.com/news/article/A2026102809050000341) (2026-10-28)
- Yonhap News, [“Bithumb, Mirae Asset Global Investments, and Daishin Securities also hit by hacking incidents… Authorities launch on-site inspections (updated, second report)”](https://www.yna.co.kr/view/AKR20261028053252002?input=1195m) (2026-10-28)
- The Chosun Ilbo, [“Daishin Securities leaks personal and credit information of 38,490 customers”](https://www.chosun.com/economy/stock-finance/2026/10/28/PU3LDIGNEZF6BLWUUQFOJ52KOM/?utm_source=naver&utm_medium=referral&utm_campaign=naver-news) (2026-10-28)
- KBS, [“Daishin Securities leaks over 38,000 records of customer information… emergency response measures”](https://news.kbs.co.kr/news/pc/view/view.do?ncd=8697211) (2026-10-28)
- Sidae, [“Daishin Securities data breach exposes 38,490 customers’ information, including account numbers”](https://www.sidae.com/article/2026102809012598578) (2026-10-28)
- The Korea Economic Daily, [“Bithumb, Daishin Securities, and Mirae Asset Global Investments breached… Financial sector’s ‘security catastrophe’ [Full report]”](https://www.hankyung.com/article/2026102800026) (2026-10-28)
- Opinion News, [“Daishin Securities, Mirae Asset Global Investments, and even Bithumb hit by ‘hacking’… ‘Investigating the scope of the breach’”](http://www.opinionnews.co.kr/news/articleView.html?idxno=146301) (2026-10-28)

## Verified facts

- Daishin Securities announced on October 28, 2026, that the personal and credit information of 38,490 customers had been leaked. (Multiple sources, including Hankook Ilbo, Yonhap News, KBS, Sidae, Hankyung, and Chosun Ilbo headlines)
- On October 17, Daishin Securities detected signs of abnormal access by a hacker to a server linked to the opening of non-face-to-face securities accounts for investment-discretionary services. (Hankook Ilbo, Yonhap News, KBS, Sidae, Hankyung)
- Daishin Securities blocked the IP address used in the attack and IP addresses used to route the connection, reported the incident to regulators, and conducted a detailed investigation into the scope of the breach with the Financial Security Institute. (Hankook Ilbo, KBS, Sidae, Hankyung, Opinion News)
- The eight types of leaked information were customers’ names, email addresses, home addresses, telecommunications IDs, bank names, deposit and withdrawal account numbers, Daishin Securities comprehensive account numbers, and mobile phone numbers. The deposit and withdrawal account numbers, comprehensive account numbers, and mobile phone numbers were encrypted. (Hankook Ilbo, KBS, Sidae, Hankyung)
- Daishin Securities said that, to date, it had found no signs of secondary damage or illegal access by hackers to core business systems. (Hankook Ilbo, KBS, Sidae, Hankyung)
- Daishin Securities said it would individually notify affected customers of the leaked information and compensate them for any damages in accordance with relevant laws and procedures. It also said it would strengthen server access controls and systems for detecting and blocking suspicious activity, and step up security checks for externally connected systems. (Hankook Ilbo, KBS, Sidae, Hankyung)
- Daishin Securities CEO Jin Seung-wook said the company took the leak very seriously and deeply apologized. (Hankook Ilbo, Sidae, Hankyung, Opinion News)
- Bithumb detected abnormal access by an unauthorized external party to its internal mobile groupware system and reported it to KISA and the Personal Information Protection Commission. It is analyzing the exact scope of the leak, including whether general member information was involved. (Hankook Ilbo, Yonhap News, Hankyung, Opinion News)
- Mirae Asset Global Investments also detected signs of an external hacking incident and is investigating its scope and circumstances. (Hankook Ilbo, Yonhap News, Hankyung, Opinion News)
- Earlier, a personal information leak at Mirae Asset Life Insurance was confirmed on October 26. (Yonhap News, Hankyung, Opinion News)
- The Financial Supervisory Service sent on-site inspection teams to Daishin Securities and Bithumb. (Yonhap News report; independently confirmed)
- At a meeting with the chairs of bank holding company boards on the 28th, Financial Supervisory Service Governor Lee Chan-jin said that as AI is being used as a hacking tool, simultaneous attacks would become commonplace, and urged boards to take the lead in strengthening IT security. (Yonhap News, Hankyung)
- Daishin Securities confirmed the leak after examining more than 60,000 signals disguised as legitimate service requests over approximately ten days. (Sidae, Hankyung)

## Points of dispute

- Sources differ on when Bithumb became aware of the incident. Hankook Ilbo, Yonhap News, and Hankyung said “the previous day” (which could be read as October 26 or 27, depending on the report’s reference point), while Opinion News said “on the 27th.” Since “the previous day” in an October 28 report means October 27, the accounts are likely consistent in practice.
- Regarding when Daishin Securities confirmed the leak, Sidae and Hankyung said it had confirmed the exposure of 38,490 people’s information as of the 26th; other outlets did not specify when it was confirmed. Opinion News wrote that the leak at Daishin Securities was confirmed “on the same day” (the 26th), although Daishin Securities announced it on the 28th.
- Sources differ on the scope of the leak at Mirae Asset Global Investments. Yonhap News reported that it was limited to information used in some work systems and that no unique identifying information, sensitive information, or personal credit information had been leaked. Hankyung said the details and scale of any leak had not been confirmed, while Hankook Ilbo only said the company was investigating who was affected and the scope of the breach.