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Category Archives for "Security"

Configuring Raspberry Pi as a router

I'm setting up a little test network for IoT devices, one isolated a bit from my home network. This is a perfect job for a computer like the Raspberry Pi (or similar computers, such as the Odroid-C2, which is what I'm actually using here). I thought I'd blog the setup details in case anybody else wanted to setup their own isolated home network.

Choice of hardware

The Raspberry Pi B v3 is a fine choice, but there are many alternatives. I'm using the Odroid C2 instead. It's nearly the same, but the chief difference for my purposes is that the Ethernet adapter is native. On the RPi, the Ethernet adapter is actually connected via USB. Network utilities don't like USB Ethernet as much.

The choice of hardware dictates the operating system. Download the latest version of Ubuntu for the Odroid C2. They keep moving around where to get it, but you can google "odroid c2 downloads" to find it. My version is Ubuntu MATE 16.04 LTS.


Your home network

Your home network likely uses the addresses 192.168.1.xxx. This is also the range that most of the devices I'm testing will use as their initial defaults. Therefore, Continue reading

Reaction: DevOps and Security

Over at TechBeacon, my friend Chris Romeo has an article up about DevOps and security. It’s interesting to me because this is actually an area I’d never thought about before, even though it makes sense. Given DevOps is essentially writing software to control infrastructure (like routers, compute, and storage), and software needs to be written in a way that is secure, then it should be obvious that DevOps software should be developed with good security principles gleaned from software development as part of the foundation.

And here we face a challenge, as Chris says—

There is no standard that defines security for DevOps, and the chances of a standard ever developing is small because different organizations are doing things their own way, and can’t even agree on a standard name. And while there is a standard for the secure development lifecycle (ISO/IEC 27034-1), few organizations are ever validated against it.

The key point in here is that every organization is doing things their own way. This isn’t wrong, of course, because every organization must have some “snowflakiness” to justify its existence, and that “snowflakiness” is often likely to show up, in a large way, in something like handling resources within Continue reading

Lamers: the problem with bounties

In my last two posts, I pointed out that the anti-spam technique known as "DKIM" cryptographically verifies emails. This can be used to verify that some of the newsworthy emails are, indeed, correct and haven't been doctored. I offer a 1 btc (one bitcoin, around ~$600 at current exchange rates) bounty if anybody can challenge this assertion.

Unfortunately, bounties attract lamers who think they deserve the bounty. 


This guy insists he wins the bounty because he can add spaces to the email, and add fields like "Cc:" that DKIM doesn't check. Since DKIM ignores extra spaces and only checks important fields, these changes pass. The guy claims it's "doctored" because technically, he has changed things, even though he hasn't actually changed any of the important things (From, Date, Subject, and body content).

No. This doesn't qualify for the bounty. It doesn't call into question whether the Wikileaks emails say what they appear to say. It's so obvious that people have already contacted me and passed on it, Continue reading

Politifact: Yes we can fact check Kaine’s email

This Politifact post muddles over whether the Wikileaks leaked emails have been doctored, specifically the one about Tim Kaine being picked a year ago. The post is wrong -- we can verify this email and most of the rest.

In order to bloc spam, emails nowadays contain a form of digital signatures that verify their authenticity. This is automatic, it happens on most modern email systems, without users being aware of it.

This means we can indeed validate most of the Wikileaks leaked DNC/Clinton/Podesta emails. There are many ways to do this, but the easiest is to install the popular Thunderbird email app along with the DKIM Verifier addon. Then go to the Wikileaks site and download the raw source of the email https://wikileaks.org/podesta-emails/emailid/2986.

As you see in the screenshot below, the DKIM signature verifies as true.


If somebody doctored the email, such as changing the date, then the signature would not verify. I try this in the email below, changing the date from 2015 to 2016. This causes the signature to fail.


There are some reasons DKIM might fail, specifically if the sender uses short keys. This doesn't apply to GMail, which uses strong 2048 bit keys, Continue reading

Yes, we can validate the Wikileaks emails

Recently, WikiLeaks has released emails from Democrats. Many have repeatedly claimed that some of these emails are fake or have been modified, that there's no way to validate each and every one of them as being true. Actually, there is, using a mechanism called DKIM.

DKIM is a system designed to stop spam. It works by verifying the sender of the email. Moreover, as a side effect, it verifies that the email has not been altered.

Hillary's team uses "hillaryclinton.com", which as DKIM enabled. Thus, we can verify whether some of these emails are true.

Recently, in response to a leaked email suggesting Donna Brazile gave Hillary's team early access to debate questions, she defended herself by suggesting the email had been "doctored" or "falsified". That's not true. We can use DKIM to verify it.

You can see the email in question at the WikiLeaks site: https://wikileaks.org/podesta-emails/emailid/5205. The title suggests they have early access to debate questions, and includes one specifically on the death penalty, with the text:
since 1973, 156 people have been on death row and later set free. Since 1976, 1,414 people have been executed in the U.S

Some notes on today’s DNS DDoS

Some notes on today's DNS outages due to DDoS.

We lack details. As a techy, I want to know the composition of the traffic. Is it blindly overflowing incoming links with junk traffic? Or is it cleverly sending valid DNS requests, overloading the ability of servers to respond, and overflowing outgoing link (as responses are five times or more as big as requests). Such techy details and more make a big difference. Was Dyn the only target? Why were non-Dyn customers effected?

Nothing to do with the IANA handover. So this post blames Obama for handing control of DNS to the Russians, or some such. It's silly, and not a shred of truth to it. For the record, I'm (or was) a Republican and opposed handing over the IANA. But the handover was a symbolic transition of a minor clerical function to a body that isn't anything like the U.N. The handover has nothing to do with either Obama or today's DDoS. There's no reason to blame this on Obama, other than the general reason that he's to blame for everything bad that happened in the last 8 years.

It's not a practice attack. A Bruce Schneier post created Continue reading

Do You Use SSL between Load Balancers and Servers?

One of my readers sent me this question:

Using SSL over the Internet is a must when dealing with sensitive data. What about SSL between data center components (frontend load-balancers and backend web servers for example)? Does it make sense to you? Can the question be summarized as "do I trust my Datacenter network team"? Or is there more at stake?

In the ideal world in which you’d have a totally reliable transport infrastructure the answer would be “There’s no need for SSL across that infrastructure”.

Read more ...

Cliché: Security through obscurity (again)

This post keeps popping up in my timeline. It's wrong. The phrase "security through/by security" has become such a cliché that it's lost all meaning. When somebody says it, they are almost certainly saying a dumb thing, regardless if they support it or are trying to debunk it.

Let's go back to first principles, namely Kerckhoff's Principle from the 1800s that states cryptography should be secure even if everything is known about it except the key. In other words, there exists no double-secret military-grade encryption with secret algorithms. Today's military crypto is public crypto.

Let's apply this to port knocking. This is not a layer of obscurity, as proposed by the above post, but a layer of security. Applying Kerkhoff's Principle, it should work even if everything is known about the port knocking algorithm except the sequence of ports being knocked.

Kerkhoff's Principle is based on a few simple observations. Two relevant ones today are:
* things are not nearly as obscure as you think
* obscurity often impacts your friends more than your enemies
I (as an attacker) know that many sites use port knocking. Therefore, if I get no response from an IP address (which I have reason Continue reading

Why cybersecurity certifications suck

Here's a sample question from a GIAC certification test. It demonstrates why such tests suck.
The important deep knowledge you should know about traceroute how it send packets with increasing TTLs to trace the route.

But that's not what the question is asking. Instead, it's asking superfluous information about the default behavior, namely about Linux defaults. It's a trivia test, not a knowledge test. If you've recently studied the subject, your course book probably tells you that Linux traceroute defaults to UDP packets on transmit. So, those who study for the test will do well on the question.

But those with either a lot of deep knowledge or practical experience will find this question harder. Windows and Linux use different defaults (Windows uses ICMP ECHOs, Linux uses UDP). Personally, I'm not sure which is which (well, I am now, 'cause I looked it up, but I'm likely to forget it again soon, because it's a relatively unimportant detail).

Those with deep learning have another problem with the word "protocol". This question uses "protocol" in one sense, where only UDP, TCP, and ICMP are valid "protocols".

But the word can be used in another sense, where "Echo" and "TTL" are also Continue reading
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