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kro

252 karma · joined July 4, 2021

github.com/kronthto
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kro··on We Took over ChatGPT Accounts
Yes, if it requires the user session (xss related), like the article, there is no problem.

I was replying more generally about the "don't click links" advice and cases of server generated confirmation-token links (not saying this was the case at OpenAI)

kro··on Do the math: How we took over ChatGPT accounts
If they or their company use email "security" software that "scans" all links it's not necessarily the users fault / they don't in fact click. The mail is auto-confirmed the second it hits the inbox.

We've had to change our registration confirmation mails too recently to not confirm on GET only, but with another form - in hindsight it was stupid before but many services do that.

kro··on Claude Haiku 5.5
Last time I gave that a try (without LLM assistance though) it was really hard as games DirectX calls cannot simply be glued to WebGL so performance was bad.
kro··on What I learned by putting GitHub Copilot behind a MitM proxy
Out of curiosity: How?

They don't offload TLS to the kernel, do they? Most apps do it in userspace linked against openssl afaik.

Do you patch that lib? If ebpf "just" operates at network/packet level, I don't see how it can do more than Mitmproxy in regard to avoid DH-PFS/Pinning

kro··on A year of fighting scrapers on my 1.5 million-page website
It does not even require the PoW thing Anubis does. I've setup a simple logic that just:

Checks for existence of a specific static cookie, if it does not exist, output a small page that sets the cookie via JS and reloads. Sadly this kills Noscript, but it would be possible to add a form in <noscript> that when submitted sets the cookie serverside.

Is this trivial to bypass? Yes. It still keeps out 95% of unwanted bots. Reality is most do not target you specifically they just want to mass-scrape with low effort. Running headless browsers is way more expensive for their op

I've extended this with a FCRDNS checked exclusion for Googlebot.

Another quite effective measure I figured out was checking the existence of Sec-Fetch-Dest header if the User-Agent claims to be a modern browser. If you don't want to close down too much.

Also, I only apply these rules to routes that are not cheap and cached.

kro··on Show HN: ssh ssh.place
I understand that most people don't use it and indeed rely on tofu, but the statement is not absolutely correct.

ssh server keys can be authenticated using (the DNSSEC "CA" system and) SSHFP, and it's possible to setup a signing CA for the host key (similar to ssh certificates, however not applicable for foreign servers). And of course, the fingerprint could be advertised out of band e.g. on the homepage with tls

kro··on CVE-2026-42530 – Nginx HTTP3/QUIC Use-After-Free
Only 1.31.0 and 1.31.1 are affected.
kro··on CVE-2026-42530 – Nginx HTTP3/QUIC Use-After-Free
These commits [1] are related to the issue. I am not too familiar with the code, but it appears nginx manages/closes streams in a pool at times the attacker cannot control, and during short windows, it is vulnerable.

[1]:

https://github.com/nginx/nginx/commit/ceccdbd2ee799d020a371b...

https://github.com/nginx/nginx/commit/9e293766e73c469c015df5...

kro··on Linux 7.1
I did that for a while because of compatibility issues with a newer laptop, it works but generally if there is no reason it's way easier to stay with the provided packages. Compiling weekly due to security patches becomes annoying over time for no real gain other than the version number
kro··on The only scalable delete in Postgres is DROP TABLE
mysql/maria also lets you turn off/down the isolation level for queries if you know the guarantees aren't needed, to speed things up. I think postgres does not have that option.
kro··on Scammers are abusing an internal Microsoft account to send spam links
I've been receiving loads of spam from google MX servers lately until blocking all mails with X-Google-Group-Id headers. I don't know how it's possible, the contents were 100% spammer controlled, no Google template
kro··on Scammers are abusing an internal Microsoft account to send spam links
You are correct.

Reminds me, we once got a letter by a German government body requesting some data exports from our company, and to upload them on findrive-ni.de

It turned out to be legit, but it's neither a subdomain of the state of Niedersachsen domain nor referenced in their official sites.

kro··on PHP's Oddities
That also often shoots you as when json_encoding it only becomes an array when ordered "correctly" (numeric 0-based keys without gaps), otherwise an object. So to be safe you generally need to array_values after filtering. If in your testdata you only remove elements from the end you don't catch that before production data hits.

To get the first element there also is reset().

I love PHP though.

kro··on Security researcher says Microsoft built a Bitlocker backdoor, releases exploit
Sounds good - which software supports this? Specifically I'd prefer if it would do a composite key derivation in-time rather than "just a pw prompt but TPM has the full key"
kro··on Security researcher says Microsoft built a Bitlocker backdoor, releases exploit
Ubuntu also released TPM based FDE a few versions ago. I had these thoughts then and decided against using it. Typing my passphrase on boot is muscle memory and gives me simple security I can trust.

Also can recover data without my mainboard.

Maybe a hybrid (secureboot-TPM+phrase) slot for day to day to also prevent against evil maid attacks, and another slot with a backup passphrase would be acceptable.

kro··on New Nginx Exploit
No remotely reachable vuln should be taken lightly.

At the moment though, the preconditions look odd. I've been using nginx in various constellations for 10 years and never once combined rewrite and set.

kro··on You gave me a u32. I gave you root. (io_uring ZCRX freelist LPE)
However, some privs can be gained in namespaces/unshare.
kro··on Dead.Letter (CVE-2026-45185) – How XBOW found an unauthenticated RCE on Exim
It says coordinated distro release today, and I've received a notice earlier today but that does not include the CVE number. That's confusing / does not seem very coordinated to release 2 separate security update notices in a day.

https://lists.debian.org/debian-security-announce/2026/msg00...

kro··on Postmortem: TanStack NPM supply-chain compromise
Next easy attack vector is (non-rootless) docker run with rootfs mount, many are in docker group even when sudo is protected. Also, most sensitive data is in the user scope anyways (on a PC).

You should always run dev stuff in containers to start with. And when your system is compromised, reprovision from a higher scope, too many places to hide backdoors

kro··on AWS to also block ipcomp and xfrm modules in DirtyFrag mitigation
So far all the information suggested to disable esp and rxrpc modules.

This bulletin suggest that more modules are necessary for complete mitigation

kro··on You gave me a u32. I gave you root. (io_uring ZCRX freelist LPE)
Containers, even with root user, are often stripped of these capabilities unless --privileged
kro··on EU Parliamentary Research Service calls VPNs "a loophole that needs closing"
VPN usage increased, but how to they draw the conclusion that this is children. I think it's more likely that adults are using VPNs to not have to deal with the ID process. I would do that.

As VPNs usually cost some money, which is already a barrier for minors.

kro··on You gave me a u32. I gave you root. (io_uring ZCRX freelist LPE)
CAP_NET/SYS_ADMIN is required for this. So this would be "not as bad" as the others.
kro··on Dirtyfrag: Universal Linux LPE
It's scary to think that some day it will be more than a local attack vector. I don't want to imagine the fallout from a remote rce via tcp/ip.
kro··on Maybe you shouldn't install new software for a bit
These copyfail exploits allow an unprivileged (daemon/app) user (not in sudoers) to get root without interaction from the original system maintainer.

It's quite different from PATH-injecting an already privileged user.

Also, these memory corruptions can likely be used as container escape primitives too. Albeit not easily.

It's a serious break of a security boundary. Yes, container layer adds defense, and normal unix security isn't perfect, but it should not allow this.

kro··on Dirty Frag: Universal Linux LPE
Maybe it would be reasonable for sysadmins to proactively whitelist used / block all exotic unused modules that are not needed in their system configuration.

This would reduce the amount of ring 0 code. But I've never seen such advice.

kro··on For Linux kernel vulnerabilities, there is no heads-up to distributions
That is true, but if at least the widely used ones would get notified before that would be beneficial. If they have a responsible security contact point.

- Debian

- Ubuntu

- Arch

- Amazon/Azure

- Fedora/RHEL

kro··on Copy Fail
Major os vendors will publish pages with the fixed versions:

https://security-tracker.debian.org/tracker/CVE-2026-31431

https://ubuntu.com/security/CVE-2026-31431

Also, disabling algif_aead is suggested as mitigation

kro··on Copy Fail
This can likely be shipped as binary code without dependencies like python, as the bug is in the kernel.
kro··on Online age verification is the hill to die on
Young people setting up a MITM and getting deeper into tech rather than consuming short-form-content is something I'd appreciate as a nice bonus effect.

Of course the EU solution isn't perfect and there are bypasses (there will always be and have always been), but let's appreciate it that way rather than too many PII, if it must come. I'd prefer the Age/RTA header and parental responsibility too.

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