Organizations running large fleets of production Linux computers are being urged to apply new patches to stop remote attackers from crashing the machines. Three flaws affect how the Linux kernel handles TCP networking and one affects the FreeBSD TCP stack.
The most serious of the four flaws, CVE-2019-11477, is called SACK Panic, referring to the Linux kernel’s TCP Selective Acknowledgement (SACK) capabilities.
Remote attackers can exploit this flaw to trigger a kernel ‘panic’ that could crash a machine, leading to a denial of service. This affects Linux kernel versions from 2.6.29 and above.
Netflix detailed the bugs in an advisory posted on GitHub and has collectively rated them as critical-severity flaws. However, RedHat individually rates SACK Panic as having an ‘important’ severity, while the remaining bugs are considered ‘moderate’.
But Netflix’s critical rating would make sense if remote attackers could down the video-streaming giant’s Linux machines, which are likely hosted on Amazon Web Services (AWS) infrastructure.
On that note, AWS has released updates for the three Linux bugs, which affected AWS Elastic Beanstalk, Amazon Linux, Linux-based EC2 instances, Amazon Linux WorkSpaces, and Amazon’s Kubernetes container service.
Some services, such as Amazon ElastiCache are not vulnerable if left in default settings, but could be if customers have changed a configuration.
The other bugs include CVE-2019-11478 or SACK Slowness, which affects Linux 4.15 and below, CVE-2019-5599, another SACK Slowness bug that affects FreeBSD 12, and CVE-2019-11479, which causes excess resource consumption.
The three Linux flaws are related and affect how the kernel handles TCP SACK packets with low Maximum Segment Size (MSS). RedHat notes in its advisory that the impact is limited to denial of service “at this time” and that it can’t be used for privilege escalation of leaking information.
SACK is a mechanism used to improve network inefficiencies caused by TCP packet loss between sender and receiver.
The engineers who drew up SACK in a IETF- standard explain: “TCP may experience poor performance when multiple packets are lost from one window of data. With the limited information available from cumulative acknowledgments, a TCP sender can only learn about a single lost packet per round trip time. An aggressive sender could choose to retransmit packets early, but such retransmitted segments may have already been successfully received.
“A Selective Acknowledgment (SACK) mechanism, combined with a selective repeat retransmission policy, can help to overcome these limitations. The receiving TCP sends back SACK packets to the sender informing the sender of data that has been received. The sender can then retransmit only the missing data segments.”
The crash can happen due to a data structure used in Linux TCP implementations called Socket Buffer (SKB), which is capable of holding up to 17 fragments of packet data, according to RedHat.
Once that limit is reached, the result can be a kernel panic issue. The other factor is MSS, or the maximum size parameter, which specifies the total amount of data contained in a reconstructed TCP segment.
“A remote user can trigger this issue by setting the Maximum Segment Size (MSS) of a TCP connection to its lowest limit of 48 bytes and sending a sequence of specially crafted SACK packets. Lowest MSS leaves merely eight bytes of data per segment, thus increasing the number of TCP segments required to send all data,” explains RedHat.
More on Linux security
Five Top Tips for Radar Briefings
Inspired by Harley Manning’s excellent advice on vendor briefings for evaluations, I thought I would document some of my recent experiences. Let’s be realistic: GigaOm is not the gorilla in the analyst market. Plus, we have some curious differences from other analyst firms — not least that we major in practitioner-led evaluation, bringing in an expert rather than (as Chris Mellor points out) “a team of consultants”. Nothing wrong with either approach, as I have said before, they’re just different.
So, what would be my top tips for vendors looking to brief us for a Radar report?
1. Make it technical
At GigaOm we care less about market share or ‘positioning’, and more about what the product or solution actually does. Our process involves considerable up-front effort pulling together, and peer reviewing a research proposal, following which (every time) we produce a Key Criteria report — for subscribers, this offers a how-to guide for writing an RFP.
By the time we’re onto the Radar, we’re mainly thinking, “Does it do the thing, and how well?” If we can get our technical experts in a virtual room with your technical experts, we can all get out of the way. See also: provide a demo.
2. Understand the scoring
Behind GigaOm’s model is a principle that technology commoditizes over time: this year’s differentiating product feature may be next year’s baseline. For this reason, we score against a general level, with two plusses given if a vendor delivers on a feature or quality. A vendor doing better than the rest will gain points (and we say why), and the converse is true. If we’re saying something, we need to be able to defend it — in this case, in the strengths and weaknesses in the report.
3. Make it defensible
Speaking of which, a vendor can make our lives simpler by telling us why a particular feature is better than everyone else’s. Sorry, we’re not looking for an easy ride, but to say what makes something special gives us something to talk about (as opposed to “but everyone thinks so,” etc). Note that customer proof points carry much more weight than general statements — if a customer says it to us directly, we’re far more likely to take it on board.
4. Tell us scenarios
At GigaOm, we’re scenario-led — which means we’re looking at how technology categories address particular problems. Many vendors solve specific problems particularly well (note, I don’t believe there’s such a thing as a top-right shortlist of vendors to suit all needs). Often in briefings, I ask ‘magic’ questions like, “Why do your customers love you?” which cut through generalist website hype and focus on where the solution is particularly strong.
5. Focus on the goal
A Radar briefing shouldn’t be perceived as a massive overhead — we want to know what your product does, not how well your media-trained speakers can present. Once done, our experts will be able to complete their work, then run the resulting one-pager back past you for a fact check. For sure, we’d love as much information as you can provide, and we have an extensive set of questionnaires for that purpose.
I’ve just flicked back through Harley’s ten points, and there’s a lot in there about being respectful, aiming to hit dates, not arguing over every judgment, and so on. Wise words, which we get just as often, I wager. I also recognize that even as we have published schedules, methodologies, planned improvements, and so on, you also have your own challenges and priorities.
All of which means that together, our primary goals should be effectiveness, such that we are presenting you, the vendor, correctly with respect to the category, and efficiency, in that a small amount of effort in the right places can benefit all of us. Which probably means, let’s talk.
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Achieve more with GigaOm
As we have grown substantially over the past two years. We are often asked who (even) is GigaOm, what the company does, how it differentiates, and so on. These are fair questions—many people still remember what we can call GigaOm 1.0, that fine media company born of the blogging wave.
We’ve been through the GigaOm 2.0 “boutique analyst firm” phase, before deciding we wanted to achieve more. That decision put us on a journey to where we are today, ten times the size in terms of headcount and still growing, and covering as many technology categories as the biggest analyst firms.
Fuelling our growth has been a series of interconnected decisions. First, we asked technology decision-makers —CIOs, CTOs, VPs of Engineering and Operations, and so on—what they needed, and what was missing: unanimously, they said they needed strategic technical information based on practical experience, that is, not just theory. Industry analysts, it has been said, can be like music critics who have never played in an orchestra. Sure, there’s a place for that, but it leaves a gap for practitioner-led insights.
Second, and building on this, we went through a test-and-learn phase to try various report models. Enrico Signoretti, now our VP of Product, spearheaded the creation of the Key Criteria and Radar document pair, based on his experience in evaluating solutions for enterprise clients. As we developed this product set in collaboration with end-user strategists, we doubled down on the Key Criteria report as a how-to guide for writing a Request For Proposals.
Doing this led to the third strand, expanding this thinking to the enterprise decision-making cycle. Technology decision-makers don’t wake up one morning and say, “I think I need some Object Storage.”
Rather, they will be faced with a challenge, a situation, or some other scenario – perhaps existing storage products are not scaling sufficiently, applications are being rationalized, or a solution has reached the end of life. These scenarios dictate a nhttps://gigaom.com/end-user-products/btis/eed: often, the decision maker will not only need to define a response but will also then have to justify the spending.
This reality dictates the first product in the GigaOm portfolio, the GigaBrief, which is (essentially) a how-to guide for writing a business case. Once the decision maker has confirmed the budget, they can get on with writing an RFP (cf the Key Criteria and Radar), and then consider running a proof of concept (PoC).
We have a how-to guide for these as well, based on our Benchmarks, field tests, and Business Technology Impact (BTI) reports. We know that, alongside thought leadership, decision-makers need hard numbers for costs and benefits, so we double down on these.
For end-user organizations, our primary audience, we have therefore created a set of tools to make decisions and unblock deployments: our subscribers come to us for clarity and practitioner-led advice, which helps them work both faster and smarter and achieve their goals more effectively. Our research is high-impact by design, which is why we have an expanding set of partner organizations using it to enable their clients.
Specifically, learning companies such as Pluralsight and A Cloud Guru use GigaOm reports helping subscribers set direction and lock down the solutions they need to deliver. By its nature, our how-to approach to report writing has created a set of strategic training tools, which directly feed more specific technical training.
Meanwhile, channel companies such as Ingram Micro and Transformation Continuum use our research to help their clients lock down the solutions they need, together with a practitioner-led starting point for supporting frameworks, architectures, and structures. And we work together with media partners like The Register and The Channel Company to support their audiences with research and insights.
Technology vendors, too, benefit from end-user decision makers that are better equipped to make decisions. Rather than generic market making or long-listing potential vendors, our scenario-led materials directly impact buying decisions, taking procurement from a shortlist to a conclusion. Sales teams at systems, service, and software companies tell us how they use our reports when discussing options with prospects, not to evangelize but to explore practicalities and help reach a conclusion.
All these reasons and more enable us to say with confidence how end-user businesses, learning, channel and media companies, and indeed technology vendors are achieving more with GigaOm research. In a complex and constantly evolving landscape, our practitioner- and scenario-led approach brings specificity and clarity, helping organizations reach further, work faster and deliver more.
Our driving force is the value we bring; at the same time, we maintain a connection with our media heritage, which enables us to scale beyond traditional analyst models. We also continue to learn, reflect, and change — our open and transparent model welcomes feedback from all stakeholders so that we can drive improvements in our products, our approach, and our outreach.
This is to say, if you have any thoughts, questions, raves, or rants, don’t hesitate to get in touch with me directly. My virtual door, and my calendar, are always open.
The post Achieve more with GigaOm appeared first on GigaOm.
Pragmatic view of Zero Trust
Traditionally we have taken the approach that we trust everything in the network, everything in the enterprise, and put our security at the edge of that boundary. Pass all of our checks and you are in the “trusted” group. That worked well when the opposition was not sophisticated, most end user workstations were desktops, the number of remote users was very small, and we had all our servers in a series of data centers that we controlled completely, or in part. We were comfortable with our place in the world, and the things we built. Of course, we were also asked to do more with less and this security posture was simple and less costly than the alternative.
Starting around the time of Stuxnet this started to change. Security went from a poorly understood, accepted cost, and back room discussion to one being discussed with interest in board rooms and at shareholder meetings. Overnight the executive level went from being able to be ignorant of cybersecurity to having to be knowledgable of the company’s disposition on cyber. Attacks increased, and the major news organizations started reporting on cyber incidents. Legislation changed to reflect this new world, and more is coming. How do we handle this new world and all of its requirements?
Zero Trust is that change in security. Zero Trust is a fundamental change in cybersecurity strategy. Whereas before we focused on boundary control and built all our security around the idea of inside and outside, now we need to focus on every component and every person potentially being a Trojan Horse. It may look legitimate enough to get through the boundary, but in reality it could be hosting a threat actor waiting to attack. Even better, your applications and infrastructure could be a time bomb waiting to blow, where the code used in those tools is exploited in a “Supply Chain” attack. Where through no fault of the organization they are vulnerable to attack. Zero Trust says – “You are trusted only to take one action, one time, in one place, and the moment that changes you are no longer trusted and must be validated again, regardless of your location, application, userID, etc”. Zero Trust is exactly what it says, “I do not trust anything, so I validate all the things”.
That is a neat theory, but what does that mean in practice? We need to restrict users to the absolute minimum required access to networks that have a tight series of ACL’s, to applications that can only communicate to those things they must communicate with, to devices segmented to the point they think they are alone on private networks, while being dynamic enough to have their sphere of trust changed as the organization evolves, and still enable management of those devices. The overall goal is to reduce the “blast radius” any compromise would allow in the organization, since it is not a question of “if” but “when” for a cyber attack.
So if my philosophy changes from “I know that and trust it” to “I cannot believe that is what it says it is” then what can I do? Especially when I consider I did not get 5x budget to deal with 5x more complexity. I look to the market. Good news! Every single security vendor is now telling me how they solve Zero Trust with their tool, platform, service, new shiny thing. So I ask questions. It seems to me they only really solve it according to marketing. Why? Because Zero Trust is hard. It is very hard. Complex, it requires change across the organization, not just tools, but the full trifecta of people, process, and technology, and not restricted to my technology team, but the entire organization, not one region, but globally. It is a lot.
All is not lost though, because Zero Trust isn’t a fixed outcome, it is a philosophy. It is not a tool, or an audit, or a process. I cannot buy it, nor can I certify it (no matter what people selling things will say). So that shows hope. Additionally, I always remember the truism; “Perfection is the enemy of Progress”, and I realize I can move the needle.
So I take a pragmatic view of security, through the lens of Zero Trust. I don’t aim to do everything all at once. Instead I look at what I am able to do and where I have existing skills. How is my organization designed, am I a hub and spoke where I have a core organization with shared services and largely independent business units? Maybe I have a mesh where the BU’s are distributed to where we organically integrated and staffed as we went through years of M&A, maybe we are fully integrated as an organization with one standard for everything. Maybe it is none of those.
I start by considering my capabilities and mapping my current state. Where is my organization on the NIST security framework model? Where do I think I could get with my current staff? Who do I have in my partner organization that can help me? Once I know where I am I then fork my focus.
One fork is on low hanging fruit that can be resolved in the short term. Can I add some firewall rules to better restrict VLAN’s that do not need to communicate? Can I audit user accounts and make sure we are following best practices for organization and permission assignment? Does MFA exist, and can I expand it’s use, or implement it for some critical systems?
My second fork is to develop an ecosystem of talent, organized around a security focused operating model, otherwise known as my long term plan. DevOps becomes SecDevOps, where security is integrated and first. My partners become more integrated and I look for, and acquire relationships with, new partners that fill my gaps. My teams are reorganized to support security by design AND practice. And I develop a training plan that includes the same focus on what we can do today (partner lunch and learns) with long term strategy (which may be up skilling my people with certifications).
This is the phase where we begin looking at a tools rationalization project. What do my existing tools not perform as needed in the new Zero Trust world, these will likely need to be replaced in the near term. What tools do I have that work well enough, but will need to be replaced at termination of the contract. What tools do I have that we will retain.
Finally where do we see the big, hard rocks being placed in our way? It is a given that our networks will need some redesign, and will need to be designed with automation in mind, because the rules, ACL’s, and VLAN’s will be far more complex than before, and changes will happen at a far faster pace than before. Automation is the only way this will work. The best part is modern automation is self documenting.
The wonderful thing about being pragmatic is we get to make positive change, have a long term goal in mind that we can all align on, focus on what we can change, while developing for the future. All wrapped in a communications layer for executive leadership, and an evolving strategy for the board. Eating the elephant one bite at a time.
The post Pragmatic view of Zero Trust appeared first on GigaOm.
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