Notices by Zimmie (bob_zim@infosec.exchange)

@evan @maj That’s what the state is today, but you asked what the visibility *should be*.

It seems that replies to a followers-only post *should be* visible to anybody who can see the original post.

@thomasfuchs @bart I really liked the Apple Newton Human Interface Guidelines. They included such gems as “Put your interface elements at the bottom of the window so users don’t have to cover up what they’re doing to use the interface.”

You know, the exact opposite of how touchscreen interfaces all seem to work now. Ugh.

@bart @thomasfuchs The fundamentals of interface design haven’t changed since the introduction of indirect pointing devices (mostly the mouse). People just keep ignoring them.

The research done since the introduction of indirect pointing reinforces the research done shortly beforehand, which was used to do things like write the human interface guidelines so developers knew how to write usable software.

@whitequark Getting the depth right for nerve blocks is difficult. I’ve been stuck right in a nerve bundle more times than I can count, and it’s hard not to flinch when that happens. At least doing it on yourself, you’re likely to learn the various depths of your own nerves quickly.

Good luck!

@micke @defred @evan In general, rules (e.g, the rules of a game) and processes are not copyrightable. And what is a recipe but a process of combining ingredients?

Processes can be *patented* (e.g, a process to produce a drug), and names of dishes can be trademarked. Arguably, the combination of recipes offered by a restaurant could also be trademarked.

@badnetmask People get that wrong all the time. I can’t tell you how many times I’ve had the “*NIX has many different concepts of free RAM, and they all suck.” conversation at work.

Better to alert on swap usage greater than 0 rather than memory usage. Let the system tell you if it’s actually running out of physical memory.

@static @lazerwalker Yes and no. Some things they overcommunicate to absurd degrees. I was once prescribed phenazopyridine. The prescribing doctor warned me it would make my urine look red, and it didn’t mean I was bleeding. Then the PA gave me the same warning. Then a nurse gave the same warning. Then the person working the front desk gave me the same warning. Got it again from the pharmacy tech when I dropped the prescription off. Again from another pharmacy tech when I picked it up. Then the pharmacist *called me* to give me the same warning.

After all that, the actual effect was underwhelming. Didn’t look remotely like blood.

@Genstar @whitequark Rust is popular with certain government contractors like companies which manufacture weapons and others which make surveillance systems. People from these companies have significant influence on where the language goes, and there’s concern they will pollute (or are already polluting) the developer culture around the language.

@thomasfuchs The problem is the Sacklers and the “war on drugs”. Over-prescription of opioids led to addiction, widespread addiction led to political limits, and now political limits lead to doctors being punished if they simply trust people and prescribe effective pain medication.

The solution is to decriminalize substance abuse and to instead treat it as a health issue, but the US is deeply puritanical, and much more into punishment than restoration.

@0xabad1dea Reminds me of how for a long time, my company’s mandatory bribery/corruption/money laundering/phishing training was on a different site every year which nobody outside of HR had ever heard of. They’d even announce it from brand new, sketchy-looking email aliases in messages full of typos, threatening us if we didn’t get it done that week. Every single red flag the phishing training told users to look out for.

@CppGuy @selzero @stib Also on how frequently you wash. I run my dishwasher when it’s full, which comes out to about once a week. It uses an order of magnitude less water than washing each day’s dishes that day.

Not sure about energy consumption. I don’t use the heated dry, so I suspect it’s about even with hand-washing with hot water (less water, so less energy spent heating the water, which is then spent running the motor).

@shortridge Some time later, I was no longer working tech support. I got hired to do network and firewall stuff for a fairly large company. At one point, they decided to relocate the office where a lot of the operations and monitoring staff worked. They moved the whole application monitoring team to the new building with the unproven infrastructure first, because some people in charge made very bad decisions.

The monitoring team gets to the new building, and they can’t access any of their monitoring systems. Clearly a problem with the new office, right? They go through a few environments to get to their monitoring systems, so I log in to the remote access VPN for the first one and confirm the first firewall they hit sees their traffic and isn’t dropping it.

I go to log in to the remote access VPN for the second environment, where the monitoring systems actually live. I’m able to start the connection, but it never prompts me for my credentials, and the tunnel never comes up. Huh. That’s weird.

Well, I’ll just get in through the DR version of the second environment. Connection works and it prompts me for my credentials, but it rejects them. I try again, in case I made a mistake entering the passphrase for my key, but it’s still rejected. Huh. That’s weird.

I eventually find a working way in. I’m able to ping all the relevant systems, I’m able to make TCP connections via telnet, but trying to actually use a service like SSH or MSRDP just hangs. But wait! I can connect to my firewalls via SSH! So what’s common among the broken systems?

All the broken systems are VMs. I start testing connections to other things which I know are VMs. They all behave the same. Ping works, TCP connections work, but data over the connections gets no response.

I bring in the virtualization team. Some of us drive in to the datacenter hosting the VMs giving us trouble. Someone quickly realizes the single SAN hosting all of the VMs’ drives was up, but wasn’t responding to storage requests. Effectively the drive had been pulled out of every single VM. Now we have an explanation for why all the VMs seem to be broken.

With most operating systems, the network stack is wired in RAM and can’t be swapped out. The network stack handles responding to pings and opening TCP connections on listening ports. Once a TCP connection is opened, it requests a copy of the listening service from storage to handle the connection. With storage no longer responding, the network stack never gets the copy of the service to handle the connection, so data doesn’t work.

Why couldn’t I connect to the second VPN endpoint? Well, some people in charge made very bad decisions. They had decided that since VMs are the future, the VPN endpoints in that facility should be moved from dedicated hardware to VMs stored on the SAN. They hadn’t gotten to the first VPN endpoint yet, but that environment wasn’t allowed to connect in to the second environment.

Okay, but I could connect to the other site’s VPN endpoint, and the other site didn’t have any problems. Why didn’t it accept my credentials? Well, some people in charge made very bad decisions (you may be noticing a theme!). All authentication was run through some VMs which were stored on the SAN. The VPN boxes in the working location were set to monitor the health of the authentication boxes in the failed location by pinging them. As long as they responded to ping, they were good, so the VPN boxes wouldn’t fail over to using their local authentication boxes. And a computer with its drive pulled can still respond to ping with just the network stack in RAM.

Once we realized what was going on, we physically connected to the WAN routers and added routes to prevent the two sites from reaching each other’s authentication boxes. Presto! We could now log in via the DR environment as normal. The other infrastructure teams were then able to start digging into their parts.

But why is the SAN unresponsive? Turns out this particular SAN vendor had an option for what to do under certain failure conditions: it could fail read-only or fail completely silent. This one was set to fail silent, and it had filled up.

I wasn’t directly involved in fixing the SAN. I know the manager over the SAN team had been sounding the alarm for months before it filled. I also know there were multiple levels of bad configuration, such as more space offered by LUNs than the SAN could physically provide.

Big takeaways:
1. Make sure your access to fix a system doesn’t depend on that system. It’s really easy to accidentally introduce dependency cycles, and it takes constant work to avoid them.
2. Superficial tests like whether you can ping something can’t detect some pretty major failures. More significant tests are more likely to notice the problem.
3. When something is critical to an environment, maybe have more than one of them? The SAN had internal redundancy to deal with faulty drives and so on, but all the storage was in one giant pool. Multiple SAN systems can provide a bulkhead such that breaking one would not break all VMs.

@shortridge While working tech support, I got a call on a Monday. Some VPNs which had been working on Friday were no longer working. After a little digging, we found the negotiation was failing due to a certificate validation failure.

The certificate validation was failing because the system couldn’t check the certificate revocation list (CRL).

The system couldn’t check the CRL because it was too big. The software doing the validation only allocated 512kB to store the CRL, and it was bigger than that. This is from a private certificate authority, though, and 512kB is a *LOT* of revoked certificates. Shouldn’t be possible for this environment to hit within a human lifespan.

Turns out the CRL was nearly a megabyte! What gives? We check the certificate authority, and it’s revoking and reissuing every single certificate it has signed once per second.

The revocations say all the certificates (including the certificate authority’s) are expired. We check the expiration date of the certificate authority, and it’s set to some time in 1910. What? It was around here I started to suspect what had happened.

The certificate authority isn’t valid before some time in 2037. It was waking up every second, seeing the current date was after the expiration date and reissuing everything. But time is linear, so it doesn’t make sense to reissue an expired certificate with an earlier not-valid-before date, so it reissued all the certs with the same dates and went to sleep. One second later, it woke up and did the whole process over again. But why the clearly invalid dates on the CA?

The CA operation log was packed with revocations and reissues, but I eventually found the reissues which changed the validity dates of the CA’s certificate. Sure enough, it reissued itself in 2037 and the expiration date was set to 2037 plus ten years, which fell victim to the 2038 limitation. But it’s not 2037, so why did the system think it was?

The OS running the CA was set to sync with NTP every 120 seconds, and it used a really bad NTP client which blindly set the time to whatever the NTP server gave it. No sanity checking, no drifting. Just get the time, set the time. OS logs showed most of the time, the clock adjustment was a fraction of a second. Then some time on Saturday, there was an adjustment of tens of thousands of seconds forward. The next adjustment was hundreds of thousands of seconds forward. Tens of millions of seconds forward. Eventually it hit billions of seconds backwards, taking the system clock back to 1904 or so. The NTP server was racing forward through the 32-bit timestamp space.

At some point, the NTP server handed out a date in 2037 which was after the CA’s expiration. It reissued itself as I described above, and a date math bug resulted in a cert which expired before it was valid. So now we have an explanation for the CRL being so huge. On to the NTP server!

Turns out they had an NTP “appliance” with a radio clock (i.e, a CDMA radio, GPS receiver, etc.). Whoever built it had done so in a really questionable way. It seems it had a faulty internal clock which was very fast. If it lost upstream time for a while, then reacquired it after the internal clock had accumulated a whole extra second, the server didn’t let itself step backwards or extend the duration of a second. The math it used to correct its internal clock somehow resulted in dramatically shortening the duration of a second until it wrapped in 2038 and eventually ended up at the correct time.

Ultimately found three issues:
• An OS with an overly-simplistic NTP client
• A certificate authority with a bad date math system
• An NTP server with design issues and bad hardware

Edit: The popularity of this story has me thinking about it some more.

The 2038 problem happens because when the first bit of a 32-bit value is 1 and you use it as a signed integer, it’s interpreted as a negative number in 2’s complement representation. But C has no protection from treating the same value as signed in some contexts and unsigned in others. If you start with a signed 32-bit integer with the value -1, it is represented in memory as 0xFFFFFFFF. If you then use it as an unsigned integer, it becomes the value 4,294,967,296.

I bet the NTP box subtracted the internal clock’s seconds from the radio clock’s seconds as signed integers (getting -1 seconds), then treated it as an unsigned integer when figuring out how to adjust the tick rate. It suddenly thought the clock was four billion seconds behind, so it really has to sprint forward to catch up!

In my experience, the most baffling behavior is almost always caused by very small mistakes. This small mistake would explain the behavior.

@horse @SrRochardBunson @YvanDaSilva Holding the sleep/wake button and either volume button for a few seconds also locks the phone. This may work better for people who have trouble hitting a button several times quickly.

If Siri is enabled, saying “Hey Siri, whose iPhone is this?” also locks the phone.

@Sylvhem @bea the THERAC-25 was a radiation therapy machine. Sloppy concurrency programming led to race conditions which allowed operator error to put the machine into a dangerous state. On earlier versions, hardware interlocks prevented it from firing in this state, but the hardware safeties were replaced with software to save money. Several people got massive overdoses, and a few died.

@Chrishallbeck

@alice Yeah, that sounds like a Bob thing to do.

@dalias @baldur Sure, but my point is LLMs are statistical grammar. They get syntax right almost all the time, but they don’t make any attempt at semantics.

@dalias @baldur We’ve known what is currently sold as “AI” is a dead end since at least 1956 with Chomsky’s paper Three Models for the Description of Language.

I can’t imagine how frustrating it must be for him having published on the topic for twice as long as a lot of the proponents of LLMs as AI have been alive.

@gpilz @evacide Vaccine mandates are hard to justify under a framework of absolute bodily autonomy, but the others are easy.

Drug prohibitions should be lifted. Drug abuse is a public health problem and should be handled in that framework.

Conscription should not only be stopped, it should be explicitly prohibited. That “selective service” lasted so long should be seen as a national embarrassment.

Circumcision of infants should be illegal. It’s not the parents’ call. If an adult wants to be circumcised for religious reasons, that’s their decision to make.