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heybrendan

241 karma · joined April 3, 2016

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heybrendan··on RAMBleed Attack – Reading Bits in Memory Without Accessing Them
Anyone else love how vulnerabilities these days have full on marketing-esque campaigns backing them? In any case, if it increases awareness, I'm mostly supportive.

Allow me to save some time, from TFA:

> Is there a CVE number?

> Yes, see CVE-2019-0174 [1].

[1] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0174

---

> What is RAMBleed?

> Previous attacks exploited the Rowhammer effect to write (or flip) bits in the victim's memory. RAMBleed is different in that it uses Rowhammer for reading data stored inside the computer's physical memory. As the physical memory is shared among all process in the system, this puts all processes at risk.

> What data can be read by RAMBleed?

> While the end-to-end attack we demonstrated read out OpenSSH 7.9's RSA key, RAMBleed can potentially read any data stored in memory. In practice, what can be read depends on the victim program's memory access patterns.

> What technologies are affected by RAMBleed?

> RAMBleed relies on Rowhammer-induced bit flips to read privileged memory. As such, any system that uses Rowhammer-susceptible DIMMs is vulnerable. Previous research has demonstrated bit flips on both DDR3 and DDR4 with TRR (targeted row refresh) enabled. While we demonstrated our attack on a desktop machine and an ECC enabled server machine, Rowhammer attacks have been demonstrated against both mobile devices and laptops. As such, we suspect that many classes of computers are susceptible to RAMBleed.

> How can I mitigate this issue?

> Users can mitigate their risk by upgrading their memory to DDR4 with targeted row refresh (TRR) enabled. While Rowhammer-induced bit flips have been demonstrated on TRR, it is harder to accomplish in practice.

> Memory manufacturers can help mitigate this issue by more rigorously testing for faulty DIMMs. Furthermore, publicly documenting vendor specific TRR implementations will facilitate a stronger development process as security researchers probe such implementations for weaknesses.

heybrendan··on An update on last week's customer shutdown incident
Feels like we're not hearing the entire story. Care to share more?
heybrendan··on Study Pinpoints Source of Banned Gas That Saps Ozone Layer: Eastern China
The transcript (and linked video) is only Peterson speaking.

Your feelings regarding Oz and any associated controversy are irrelevant, unless you're indirectly implying that Oz is unfit to conduct an interview, in which case, I think you've got your work cut out for you. It would be impertinent and premature to dismiss an interview simply because you dislike the host: I can easily name any number of hosts I dislike or have a general disdain for yet found the discussions interesting and/or thought-provoking.

That being said, if it's not crystal-clear at this point: it's discussion around Peterson's ideas I'm interested in, in the context of China (and the TFA). Would you care to respond to Peterson's thoughts directly?

heybrendan··on Study Pinpoints Source of Banned Gas That Saps Ozone Layer: Eastern China
This comment adds very little to the discussion. Could you provide some examples?
heybrendan··on Study Pinpoints Source of Banned Gas That Saps Ozone Layer: Eastern China
> Western corporations have done as much harm as they could get away with to make a quick buck as well.

I'm in agreement (for the most part)--historically speaking. I never said that this was purely relegated to China, although the topic of the article is indeed China.

I'll also take this opportunity to remind you about HN commenting guidelines [1], specifically when disagreeing to try to "reply to the argument", as opposed to calling names--or in your specific case implying emotional states or assumptions on worship.

I will share that I find it unfortunate that you seem generally opposed to Dr. Peterson's works: his Maps of Meaning (1999)[2], for instance, contains powerful ideas that cannot be easily dismissed.

Finally, humans are complex creatures. We can easily find an argument intrinsically stimulating and academically fascinating whilst simultaneously not feeling disillusionment.

[1] https://news.ycombinator.com/newsguidelines.html [2] https://www.amazon.com/Maps-Meaning-Architecture-Jordan-Pete...

heybrendan··on Study Pinpoints Source of Banned Gas That Saps Ozone Layer: Eastern China
TFA made me think of Dr. Mehmet Oz' interview of Dr. Jordan Peterson [1] from last year (2018). I've transcribed part of the interview below:

Dr. Jordan Peterson:

> "I've always been obsessed with totalitarianism and authoritarian governments whether they're on the Right or the Left for years--decades really. I spent almost all of my free time thinking about what happened in Nazi Germany and in Russia during the Soviet era; but also when Mao was [in] China--there were other places as well. [I was] trying to understand how it was that we could have got off the rails so absolutely terribly. I started studying that at the collectivist level, looking for political or economic reasons. But as I investigated further those levels of analysis [...] weren't providing the answers that I wanted--I think partly because I was really interested in the notion that there's something to learn from what happened, say in Nazi Germany: but there's something to learn at an individual level. That's my estimation. I don't think that there were innocent masses of people led astray by a single malevolent leader. I don't think the fundamental motivations for what happened in Nazi Germany were economic and I don't think they were in the Soviet Union either. As I read more and more about the situation, I realized that the proclivity of individuals to avoid responsibility and to lie, especially about their own lives and about their own experience, were really the reasons that those systems went so far astray."

> "[...] The lessons there for me were psychological and that taught me an awful lot about the role of the individual: people like Viktor Frankl, for example, who wrote Man's Search for Meaning, a perennial classic and a great book--insisted that a large part of the reason that Germany went off the rails so badly was because individual Germans were so willing to falsify their own experience. Alexander Solzhenitsyn who wrote the Gulag Archipelago, the best document on what happened in the Soviet Union, also made exactly the same argument."

> "So I got interested in the psychological causes of catastrophic governance and that taught me a lot. It taught me about responsibility. About the responsibility of the sovereign individual. We have an idea in our [Western] culture, it's a very powerful idea: that each of us is of intrinsic value. But associated with that value is a responsibility: we have a responsibility for our own integrity and for that of our families but also of the state."

This begs the question: are Chinese business men and women willing to falsify their own experience at the expense of the {environment,personal integrity} to make a buck and/or survive?

The business culture of dishonesty (borrowing from HN user docker_up) can't persist forever.

[1] https://youtu.be/AscPHmLWo-M?t=322

heybrendan··on Building CentOS 8
The last part of your comment seems quite absurd.

Simply put, just because you may not know of anyone in your immediate professional or social circles using RHEL, does not mean it's not extremely popular in the capital E enterprise.

AFAICT, RHEL is the Linux distribution of choice in most enterprise IT organizations /because/ of it's commitment to long-term support, stability, ABI compatibility, programs like EUS, and so forth--the list goes on.

heybrendan··on Azure is experiencing DNS issues in all regions
You didn't [make me upset]. I'm also looking forward to see what Red Hat is capable of with IBM's resources. Thanks for clarifying.
heybrendan··on Azure is experiencing DNS issues in all regions
Huh? I did not have to look very long to find evidence [1] of rather sobering issues with IBM "Cloud". In fact, that article reported IBM as dead last in the 2018 Gartner's Magic Quadrant ranking of IaaS cloud offerings.

What are you trying to say exactly? And why should customers turn their attention to IBM?

[1] https://www.theregister.co.uk/2018/07/04/ibm_cloud_outage/

heybrendan··on Facebook taps lawyer who helped write Patriot Act as new general counsel
Unrelated, "The Inner Light" episode still hits me in my soul, even after all this time. For those that have not seen it, you owe yourself to watch it.
heybrendan··on German federal office publishes Windows 10 telemetry analysis
Excellent point, and I'm well aware. Vigilance (and a proactive security posture) are the price of privacy--and I suspect nothing of actual value will be lost.

It's preferable (to me) to blacklist /everything/ and deal with any future connectivity issues on a case-by-case basis.

heybrendan··on German federal office publishes Windows 10 telemetry analysis
(More) direct link to the publication: https://www.bsi.bund.de/SharedDocs/Downloads/DE/BSI/Cyber-Si...

Page 31 of the report was of primary interest--hosts hard-coded in diagtrack.dll:

geo.settings-win.data.microsoft.com.akadns.net db5-eap.settings-win.data.microsoft.com.akadns.net settings-win.data.microsoft.com db5.settings-win.data.microsoft.com.akadns.net asimov-win.settings.data.microsoft.com.akadns.net db5.vortex.data.microsoft.com.akadns.net v10-win.vortex.data.microsft.com.akadns.net geo.vortex.data.microsoft.com.akadns.net v10.vortex-win.data.microsft.com us.vortex-win.data.microsft.com eu.vortex-win.data.microsft.com vortex-win-sandbox.data.microsoft.com alpha.telemetry.microsft.com oca.telemetry.microsft.com

At this point, I would recommend choosing to treat the {akadns.net, microsoft.com, microsft.com} TLDs with general distrust. Also in the report:

40.77.226.249 40.77.226.250 13.92.194.212 52.178.38.151 52.229.39.152 52.183.114.173 13.78.232.226

For convenience, I've enumerated the corresponding CIDRs:

13.104.0.0/14 13.64.0.0/11 13.96.0.0/13 40.112.0.0/13 40.120.0.0/14 40.124.0.0/16 40.125.0.0/17 40.74.0.0/15 40.76.0.0/14 40.80.0.0/12 40.96.0.0/12 52.145.0.0/16 52.146.0.0/15 52.148.0.0/14 52.152.0.0/13 52.160.0.0/11 52.224.0.0/11

I'm not sure how to react to the observation of the usage of "microsft.com". I'll admit my instinct is to perceive this as, at worst, a rather clandestine attempt at circumventing basic DNS black-holing techniques--in which case, well played MSFT.

Now if you'll excuse me, I have some firewall policies to update.

heybrendan··on Build a do-it-yourself home air purifier for about $25
Very interesting!

How does the Dylos 1100 Pro compare to, for example, the Nova SDS011 sensor? By my cursory review, the SDS011 is much cheaper and appears to offer a more native Raspberry Pi-compatibility experience.

Is the Dylos more precise? Can it produce readings the SDS011 can't? Are the two sensors measuring fundamentally different things?

Finally, if you had to do it all over again, would you choose a different sensor or stick with the Dylos?

Thanks for sharing your project and for your insights!

heybrendan··on Linux 4.19
Linux Kernel Newbies is certainly a great resource.

The more interesting component this cycle is the fact that the release notes were written by Greg KH--worth the read in my opinion.

heybrendan··on Show HN: A site to look up DNS records
Thanks a bunch.

I'll take a crack at implementing something similar, much appreciated!

heybrendan··on Show HN: A site to look up DNS records
Interesting--I'd like to know more.

Would you please provide example command(s) of blocking both ANY queries and NOERROR responses that you've had relative success with?

Thanks!

heybrendan··on 50 Shades of System Calls
Summoning the spirit (and more importantly the expertise) of brendangregg here.

From the home page sysdig "capture[s] system state and activity", but by leveraging specifically what?

From https://sysdig.com/blog/sysdig-vs-dtrace-vs-strace-a-technic...:

"First, events are captured in the kernel by a small driver, called sysdig-probe, which leverages a kernel facility called tracepoints."

That makes it sound like it's quite similar to the ftrace kernel tracer by instrumenting the various event tracepoints (/sys/kernel/debug/tracing/available_events) conveniently strewn throughout the kernel source--is this indeed the case?

Alternatively, is sysdig doing something differently? {k,u}probes? Sampling similar to, perhaps say, perf's capabilities?

The Linux tracing/profiling landscape is murky enough (littered with tools like SystemTap, LTTng, and so forth) and I'd like to know where this tool fits into an analysis work-flow--and more importantly, what's it's using (at a low-level) to gather data.

I'd appreciate any and all clarification.

Cheers.

heybrendan··on BCC: Dynamic Tracing Tools for Linux
New account, just to ask this.

I understand how much effort is involved in writing / publishing.

Are you planning a Second edition of your "Systems Performance, Enterprise and the Cloud" text, especially in light of the pace of development in the Linux performance / profiling space?

Thank you for all your countless contributions.

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