Cyberattack Hits Iwai Cosmo Securities — Clients Hit With Trades They Never Authorized

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The story

On October 20, Iwai Cosmo Securities and Trade Works, the firm that operates and maintains its systems, revealed that the company’s online trading system had been hit by a cyberattack, resulting in buy and sell orders that customers never intended to place. According to a report by the Asahi Shimbun, no leak of authentication data such as PINs has been confirmed, raising the possibility that attackers found a route to place orders without using login credentials at all. On the forum thread, opinions were all over the map on causes and countermeasures — whether passkeys had been rolled out, how lax security practices might have been, AI-automated attacks, and the risk of this spreading to banking or pension systems.

Tue, Oct 20, 10:21 PM

Asahi Shimbun

The online trading system of Iwai Cosmo Securities (Osaka) was hit by a cyberattack, resulting in trades customers never intended to make. The company and Trade Works (Tokyo), which handles the system’s operation and maintenance, disclosed this on the 20th.

Source: topics.smt.docomo.ne.jp / Read the original article here

What people said

7AnonymousOct 20, 2026 22:29
So how do we actually protect ourselves from cyberattacks?
35AnonymousOct 20, 2026 22:34
Re: #7
As a consumer, the surest move is to boycott profit-first companies that treat security as just a cost to minimize.
173AnonymousOct 20, 2026 23:02
Re: #7
Just go full self-isolation (sakoku, Japan's old 'closed country' policy) solo — problem solved.
15AnonymousOct 20, 2026 22:31
Wait, did they not even have passkeys set up?
219AnonymousOct 20, 2026 23:19
Re: #15
Some companies do get as far as adding passkeys, but it's pointless unless they also disable the password afterward — or set it to a random string so long even they couldn't remember it, print it out, and wipe the digital copy.
43AnonymousOct 20, 2026 22:36
So brokerages and banks are in real trouble now too? Feels like society's on the verge of collapse.
50AnonymousOct 20, 2026 22:38
Re: #43
Wasn't there a Korean bank that got hit the same way?
49AnonymousOct 20, 2026 22:37
> The unauthorized trades weren't carried out using leaked information,
> and no leak of PINs or other credentials needed for online trading has been confirmed.

So basically, there was a hole that let attackers skip authentication entirely — no ID, no password — and place orders straight from the account…
70AnonymousOct 20, 2026 22:41
Re: #49
LOL, so unauthorized access is possible without even logging in?
78AnonymousOct 20, 2026 22:42
And next up: the banks.
85AnonymousOct 20, 2026 22:44
Re: #78
Apparently most banks don't actually expose account data directly to the internet, though.
91AnonymousOct 20, 2026 22:44
Re: #78
Then pensions and the stock market are next too, right? That's capitalism done for.
82AnonymousOct 20, 2026 22:43
Couldn't someone just rewrite a regional bank's account balance pretty easily then?
99AnonymousOct 20, 2026 22:46
Re: #82
As long as balances are recorded on a computer, tampering with them isn't impossible, no.
87AnonymousOct 20, 2026 22:44
I looked into how all these recent leak incidents actually happened, and every single one came down to 'the company's fault.' AI has nothing to do with it — attackers can now just scan everything indiscriminately, and it's simply exposing which companies have paper-thin security.
122AnonymousOct 20, 2026 22:50
Re: #87
Well, AI isn't totally unrelated — thanks to AI, attackers can hit targets indiscriminately with way less effort, and that's exactly what's exposing the companies slacking on security.

Those garbage companies really should just go under, but somehow they'll end up getting bailed out 'for the sake of society'… with our tax money 🤣
103AnonymousOct 20, 2026 22:46
And yet they keep pushing to integrate bank and brokerage accounts… The Financial Services Agency doesn't seem all that competent either. Though they sure come down hard on the little guy lol
109AnonymousOct 20, 2026 22:47
Re: #103
They're also pushing to link everything to your My Number (Japan's national ID system). If that gets compromised, your money would vanish in an instant.
134AnonymousOct 20, 2026 22:52
Guess buying security stocks is the way to make money off this.
141AnonymousOct 20, 2026 22:53
Re: #134
Can't — someone else will just trade it on your behalf without asking.
244AnonymousOct 20, 2026 23:35
Re: #134
Everyone already bought in ages ago. It's on an absolute tear right now lol
143AnonymousOct 20, 2026 22:54
Just let AI handle security — it's a shield-and-spear situation anyway.
147AnonymousOct 20, 2026 22:55
Re: #143
Even the Pentagon, with supposedly world-class defenses, gets breached — offense just has the upper hand.
180AnonymousOct 20, 2026 23:03
Re: #143
The defense side can learn autonomously too, but it tends to only learn after being attacked, which puts it at a disadvantage. Worst case, an AI testing itself during autonomous learning could end up attacking other systems.
150AnonymousOct 20, 2026 22:56
This is bad enough, but just earlier there was also news about income-estimable data plus names and addresses leaking from something tied to the furusato nozei (hometown tax donation) program. The severity of these leaks keeps climbing.
166AnonymousOct 20, 2026 23:00
Re: #150
Even if what leaks from any single company isn't a big deal on its own, if the same hacker is pulling data from multiple sources, cross-referencing it by name could add up to something serious. Even just registering your name and email for a '5% off this purchase if you sign up' deal — stack enough of that kind of data and you can start guessing everything from someone's preferences to their income.
183AnonymousOct 20, 2026 23:04
This company does have passkeys set up though… hmm.
187AnonymousOct 20, 2026 23:05
Re: #183
Even if the system offers it, there are probably users who never actually turn it on, right?
195AnonymousOct 20, 2026 23:10
Re: #183
Most places have rolled out passkeys, but password login still works alongside it. Smart Securities is apparently killing password login entirely this month, though.
193AnonymousOct 20, 2026 23:09
How did they even catch this? Customer complaints? If so, there are probably cases still going unnoticed.
198AnonymousOct 20, 2026 23:10
Re: #193
Like that incident a while back — probably someone noticed a trade executed for Chinese market stocks they'd never buy.
208AnonymousOct 20, 2026 23:15
Re: #193
Apparently they detected the attack and cut off access.

Background and Key Points of the Discussion

Unauthorized access targeting brokerages’ online trading systems — resulting in stock trades customers never intended — has been reported at multiple firms since 2025, and some in the thread pointed to past cases of this kind. What Iwai Cosmo Securities emphasized this time is that authentication data such as PINs was not itself leaked, suggesting attackers may have used a different route than the conventional method of stealing IDs and passwords to impersonate users. Opinions in the thread split over whether the main driver behind this rise in attacks is AI-automated hacking or simply insufficient security investment by companies. There were also comments noting that even financial institutions that have adopted passkeys (passwordless authentication via biometrics, etc.) often keep the older password login running in parallel, meaning vulnerabilities can persist unless one method or the other is fully disabled. Note: posts containing ethnic slurs or incitement to violence toward any nationality have been excluded from this article.

*This article is excerpted and summarized from the 5ch (News Express+) thread: “[Unauthorized Trading] Cyberattack Hits Iwai Cosmo Securities — Client-Unintended Trade Orders Executed“

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