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Category Archives for "Security"

Dispersing a DDoS: Initial thoughts on DDoS protection

Distributed Denial of Service is a big deal—huge pools of Internet of Things (IoT) devices, such as security cameras, are compromised by botnets and being used for large scale DDoS attacks. What are the tools in hand to fend these attacks off? The first misconception is that you can actually fend off a DDoS attack. There is no magical tool you can deploy that will allow you to go to sleep every night thinking, “tonight my network will not be impacted by a DDoS attack.” There are tools and services that deploy various mechanisms that will do the engineering and work for you, but there is no solution for DDoS attacks.

One such reaction tool is spreading the attack. In the network below, the network under attack has six entry points.

Assume the attacker has IoT devices scattered throughout AS65002 which they are using to launch an attack. Due to policies within AS65002, the DDoS attack streams are being forwarded into AS65001, and thence to A and B. It would be easy to shut these two links down, forcing the traffic to disperse across five entries rather than two (B, C, D, E, and F). By splitting the Continue reading

The command-line, for cybersec

On Twitter I made the mistake of asking people about command-line basics for cybersec professionals. A got a lot of useful responses, which I summarize in this long (5k words) post. It’s mostly driven by the tools I use, with a bit of input from the tweets I got in response to my query.

bash

By command-line this document really means bash.

There are many types of command-line shells. Windows has two, 'cmd.exe' and 'PowerShell'. Unix started with the Bourne shell ‘sh’, and there have been many variations of this over the years, ‘csh’, ‘ksh’, ‘zsh’, ‘tcsh’, etc. When GNU rewrote Unix user-mode software independently, they called their shell “Bourne Again Shell” or “bash” (queue "JSON Bourne" shell jokes here).

Bash is the default shell for Linux and macOS. It’s also available on Windows, as part of their special “Windows Subsystem for Linux”. The windows version of ‘bash’ has become my most used shell.

For Linux IoT devices, BusyBox is the most popular shell. It’s easy to clear, as it includes feature-reduced versions of popular commands.


man

‘Man’ is the command you should not run if you want help for a command.

Man pages are designed to drive away Continue reading

Technology Short Take #76

Welcome to Technology Short Take #76, the first Technology Short Take of 2017. Normally, I’d publish this on a Friday, but due to extenuating circumstances (my mother-in-law’s funeral is tomorrow) I’m posting it today. Here’s hoping you find something useful!

Networking

About that Giuliani website…

Rumors are that Trump is making Rudy Giuliani some sort of "cyberczar" in the new administration. Therefore, many in the cybersecurity scanned his website "www.giulianisecurity.com" to see if it was actually secure from hackers. The results have been laughable, with out-of-date software, bad encryption, unnecessary services, and so on.

But here's the deal: it's not his website. He just contracted with some generic web designer to put up a simple page with just some basic content. It's there only because people expect if you have a business, you also have a website.

That website designer in turn contracted some basic VPS hosting service from Verio. It's a service Verio exited around March of 2016, judging by the archived page.

The Verio service promised "security-hardened server software" that they "continually update and patch". According to the security scans, this is a lie, as the software is all woefully out-of-date. According OS fingerprint, the FreeBSD image it uses is 10 years old. The security is exactly what you'd expect from a legacy hosting company that's shut down some old business.

You can probably break into Giuliani's server. I know this because other FreeBSD servers in the same data Continue reading

NAT is a firewall

NAT is a firewall. It's the most common firewall. It's the best firewall.

I thought I'd point this out because most security experts might disagree, pointing to some "textbook definition". This is wrong.

A "firewall" is anything that establishes a barrier between some internal (presumably trusted) network and the outside, public, and dangerous Internet where anybody can connect to you at any time. A NAT creates exactly that sort of barrier.

What other firewalls provide (the SPI packet filters) is the ability to block outbound connections, not just incoming connections. That's nice, but that's not a critical feature. Indeed, few organizations use firewalls that way, it just causes complaints when internal users cannot access Internet resources.

Another way of using firewalls is to specify connections between a DMZ and an internal network, such as a web server exposed to the Internet that needs a hole in the firewall to access an internal database. While not technically part of the NAT definition, it's a feature of all modern NATs. It's the only way to get some games to work, for example.

There's already more than 10-billion devices on the Internet, including homes with many devices, as well as most mobile phones. Continue reading

No, Yahoo! isn’t changing its name

Trending on social media is how Yahoo is changing it's name to "Altaba" and CEO Marissa Mayer is stepping down. This is false.

What is happening instead is that everything we know of as "Yahoo" (including the brand name) is being sold to Verizon. The bits that are left are a skeleton company that holds stock in Alibaba and a few other companies. Since the brand was sold to Verizon, that investment company could no longer use it, so chose "Altaba". Since 83% of its investment is in Alibabi, "Altaba" makes sense. It's not like this new brand name means anything -- the skeleton investment company will be wound down in the next year, either as a special dividend to investors, sold off to Alibaba, or both.

Marissa Mayer is an operations CEO. Verizon didn't want her to run their newly acquired operations, since the entire point of buying them was to take the web operations in a new direction (though apparently she'll still work a bit with them through the transition). And of course she's not an appropriate CEO for an investment company. So she had no job left -- she made her own job disappear.


What happened today Continue reading

Some Reading on Application Containers

One aspect of my pending migration to Ubuntu Linux on my primary laptop has been the opportunity to explore “non-traditional” uses for Linux containers. In particular, the idea of using Docker (or systemd-nspawn or rkt) to serve as a sandbox (of sorts) for GUI applications really intrigues me. This isn’t a use case that many of the container mechanisms are aiming to solve, but it’s an interesting use case nevertheless (to me, anyway).

So, in no particular order, here are a few articles I found about using Linux containers as application containers/sandboxes (mostly focused around GUI applications):

A Docker-Like Container Management using systemd
Running containers without Docker
Containerizing Graphical Applications on Linux with systemd-nspawn
Debian Containers with systemd-nspawn
Using your own containers with systemd-nspawn and overlayfs

I was successful in using Docker to containerize Firefox (see my “dockerfiles” repository on GitHub)), and was also successful in using systemd-nspawn in the same way, including the use of overlayfs. My experiments have been quite helpful and informative; I have some ideas that may percolate into future blog posts.

Response: The Orphaned Internet – Taking Over 120K Domains via a DNS Vulnerability in AWS, Google Cloud, Rackspace and Digital Ocean | The Hacker Blog

So obvious but I’m checking my unused domains to make sure they have no nameservers configured

The root of this vulnerability occurs when a managed DNS provider allows someone to add a domain to their account without any verification of ownership of the domain name itself. This is actually an incredibly common flow and is used in cloud services such as AWS, Google Cloud, Rackspace and of course, Digital Ocean. The issue occurs when a domain name is used with one of these cloud services and the zone is later deleted without also changing the domain’s nameservers. This means that the domain is still fully set up for use in the cloud service but has no account with a zone file to control it. In many cloud providers this means that anyone can create a DNS zone for that domain and take full control over the domain. This allows an attacker to take full control over the domain to set up a website, issue SSL/TLS certificates, host email, etc. Worse yet, after combining the results from the various providers affected by this problem over 120,000 domains were vulnerable (likely many more).

The Orphaned Internet – Taking Over 120K Domains via Continue reading

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