Schneier on Security

Clive Robinson • May 12, 2026 1:59 PM

@ Anonymous,

With regards,

“When a piece of software grows as big and complex as modern kernels and web browsers, can it ever be fully secured? “

The simple answer is “Yes” but…

It has to be sufficiently segregated not just from “external attackers” but “internal users” and the like.

To do this sensibly requires either “total segregation” or rather more than “air gapping”.

It was noted way back before anyone here was out of diapers that,

“For a computer to be useful it needs to be able to communicate.”

Thus the real questions are thus communicate to whom, how, and where they are…

Which is generally problematical to talk about.

Which is why I’ve talk about and still do,

1, Energy Gapping.
2, Fully mandated gap crossing.

As these represent the higher water marks of gapping a computer for security against “outside attackers”.

Note I do not talk about “insider attacks” even though they are directly or indirectly the cause of most successful security attacks on computers.

Whilst there are things that can be done about “Insider Attacks” like SE-Linux etc they generally are either not done or done insufficiently…

Which is the case with both the current attacks being talked about.

The second arriving in public over the weekend,

‘Dirty Frag’ Linux flaw one-ups CopyFail with no patches and public root exploit

Broken disclosure embargo left admins facing a fresh root-level flaw with no CVE

‘A fresh Linux privilege escalation bug dubbed “Dirty Frag” has dropped into the wild with no patches, no CVE, and a public exploit that hands attackers root access across major distributions.

Security researcher Hyunwoo Kim disclosed the local privilege escalation flaw on Friday after what he said was a broken embargo forced the issue into the open.

Kim described Dirty Frag as a “universal LPE” affecting “all major distributions” and warned that it delivers the same kind of immediate root access as the recent CopyFail mess – only this time, defenders do not even have patches to throw at the problem.

“As with the previous Copy Fail vulnerability, Dirty Frag likewise allows immediate root privilege escalation on all major distributions,” Kim said. “Because the responsible disclosure schedule and embargo have been broken, no patches exist for any distribution.”‘

https://www.theregister.com/security/2026/05/08/dirty-frag-linux-flaw-one-ups-copyfail-with-no-patches-and-public-root-exploit/5237230

Worryingly due to both –actualky three– vulnerabilities being disclosed before patches are even close, there has been “a knee jerk suggestion” in the Linux Kernal Development Space of,

Linux kernel maintainers pitch emergency killswitch after CopyFail and Dirty Frag chaos

Instead of waiting for patch cycles, admins could simply shut down vulnerable functions before attackers get there

‘Linux kernel maintainers are considering giving admins a giant red emergency button to smash the next time another nasty vulnerability drops before patches are ready.

The proposed feature, named “Killswitch,” would let admins temporarily disable specific vulnerable kernel functions at runtime instead of sitting around waiting for fixes. The so-called patch was submitted by Linux stable kernel co-maintainer and Nvidia engineer Sasha Levin after a bruising couple of weeks for Linux security.

The proposal basically gives admins a way to pull the plug on vulnerable kernel functionality. If exploit code starts spreading before patches arrive, the targeted function can be disabled so calls to it immediately fail instead of reaching the vulnerable code.

“When a (security) issue goes public, fleets stay exposed until a patched kernel is built, distributed, and rebooted into,” Levin wrote. “For many such issues the simplest mitigation is to stop calling the buggy function. Killswitch provides that.”

The past couple of weeks have not exactly been great advertising for the traditional “wait for patches” approach.‘

https://www.theregister.com/oses/2026/05/11/linux-kernel-maintainers-pitch-emergency-killswitch-after-copyfail-and-dirty-frag-chaos/5237801

For a whole load of reasons this “killswitch” idea is not actually a good one, even though it sounds alluring.

Clive Robinson • May 13, 2026 6:42 AM

@ ALL,

@Dave notes,

“Or another way of looking at it is with the aphorism that a shared/multiuser machine isn’t your computer, it’s our computer.”

Is nolonger true and has not been for quite some time due to even “run of the mill criminal attackers, having what just a decade ago was considered “State Level” “sources and methods”.

So the aphorism should be more along the lines of,

“Any computer that we can reach physically or via coherent energy is our computer.”

If you look back I’ve been warning that where people can they should have two computers,

1, The first for private work.
2, The second for communications.

Further that the communications computer should not have “mutable storage” so simply “cycling the power” would clean it of any infections.

Back when I talked about the two computer solution, computing hardware was different, as was society. Back then for the communications computer you could use an MSI or equivalent low cost “all in one” motherboard that had video and sound and basic I/O hardware built in, and all you had to add was sufficient DRAM and a DVD drive to boot off. You would then get a Linux or Similar “monthly magazine” that had a “Bootable Distribution” on it, from a “random shop” you’d not been to before, and use the DVD to boot up.

Similarly for higher security the private machine could be left as a “numb nuts” Windows machine in case it got grabbed or got at. You would actually use another bootable distribution from either a DVD or Thumb Drive and only mount a thumb drive for private storage as these were a lot lot easier to secure physically than a computer.

All you then needed was a way that was sufficiently secure to “cross the air gap” safely.

Sadly computers now are filled with semi-mutable “Flash ROM” of all kinds which can be “got at” from any “physical or coherent energy” contact. Computer Magazines with bootable distribution DVD ROMs are also a thing of the past. And as we all should know now “air-gaps” are really insufficient[1] even for ordinary people you need “energy gapps” and more complex crossing techniques.

Whilst you can still do this technology and major Corporate and Government “Data Desires” are making the use of “Personal Computers” harder and harder.

If Apple, Google, and Microsoft along with most Western Governments and their “Guard Labour” have their way, “Clint Side Scanning” will become “unavoidable” for all but the very few who are sufficiently adept and prepared to do what is required for OpSec to be reliable.

Sorry if this makes you depressed on reading, but Others and I have been warning for years that this is happening.

Further that you can not nor should not trust any consumer or commercial OS or hardware any longer. It’s not just journalists and their sources it’s

“Anyone that is seen as a potential threat or even just convenient[3]”

What does it take to be “convenient?” just,

“Carrying or using technology”

Is more than enough. Worse being forced to use technology just to be included in society just makes the potential hurt even greater, as Data brokers trade every last detail that can be extracted, or worse assumed about you.

I could go on at length about just how fast this is happening but people reading this should know how to find it easily enough, so it’s more a question of if,

“People want to face the reality of what is happening?”

Just “look behind the curtain” at what is really happening with this “proof of age” nonsense, don’t wait half a decade and then start complaining, start now.

[1] Why has this,

“Filtered down to criminals?”

Well you can blame “crypto-coins” and similar. Some criminal gangs will just smash into your home and “slice and dice” you or a close relative[2]. Others will use more technical means. Either way such criminals exist and are active and not likely to ever go away in our life times. Because all they are after is “Key information” that can be written down in a few seconds. As that information can give them “millions” they are shall we say “incentivised”…

[2] After all,

“What’s one more dead body after the first couple?”

The way the legal system works is after the first one or two all the others do not make a difference to your sentence, so effectively are “free”…

[3] Guard labour has a very long history of “framing/fitting people up” for crimes they have not committed. Mostly this happens for what can be called “political reasons”. After all “quick arrests and convictions” are very desirable not just for promotion in the ranks, but to “politicians” as well… And the politicians and most of the guard labour also know that if an “innocent person” gets convicted they won’t get the blame in five to twenty years when the truth comes out… But in the mean time their career will have been boosted or in some other way benefited, and they won’t loose that. Worse, a fat pension and a book deal etc can happen as well… We’ve seen this happen over and over so it’s more than just one aberrant individual it’s “A clear MO”.

Clive Robinson • May 13, 2026 5:07 PM

@ 420,

Funny you should say,

“Linux Magazine would like a word with you”

That was one of the magazines that you could pick up in many UK News Agents…

Hence you could just “get one at random” which had the advantage from a security aspect that you would not have it “intercepted”… And replaced with one that was potentially “back doored” whilst it was “in the post” or in the “Delivery Center” of the USPS etc.

Which at one point sounded “totally paranoid” then Ed Snowden revealed back nearly a decade and a half ago that the NSA had been backdooring routers in delivery to customers abroad for ages…