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Category Archives for "Security"

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

Trump on cybersecurity: vacuous and populist

Trump has published his policy on cybersecurity. It demonstrates that he and his people do not understand the first thing about cybersecurity.

Specifically, he wants “the best defense technologies” and “cyber awareness training for all government employees”. These are well known bad policies in the cybersecurity industry. They are the sort of thing the intern with a degree from Trump University would come up with.

Awareness training is the knee-jerk response to any problem. Employees already spend a lot of their time doing mandatory training for everything from environmental friendly behavior, to sexual harassment, to Sarbannes-Oxley financial compliance, to cyber-security. None of it has proven effective, but organizations continue to force it, either because they are required to, or they are covering their asses. No amount of training employees to not click on email attachments helps. Instead, the network must be secure enough that reckless clicking on attachments pose no danger.

Belief in a technological Magic Pill that will stop hackers is common among those who know nothing about cybersecurity. Such pills don’t exist. The least secure networks already have “the best defense technologies”. Things like anti-virus, firewalls, and intrusion prevention systems do not stop hackers Continue reading

Windows SSH client with TPM

I managed to get an SSH client working using an SSH pubkey protected by a TPM.

Optional: Take ownership of the TPM chip

This is not needed, since TPM operations only need well known SRK PIN, not owner PIN, to do useful stuff. I only document it here in case you want to do it. Microsoft recommends against it.

  1. Set OSManagedAuthLevel to 4 HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\TPM\OSManagedAuthLevel 2 -> 4

    Reboot.

  2. Clear TPM

    Run tpm.msc and choose “Clear TPM”. The machine will reboot and ask you to press F12 or something for physical proof of presence to clear it.

  3. Set owner password from within tpm.msc

Set up TPM for SSH

  1. Create key

    tpmvscmgr.exe create /name "myhostnamehere VSC" /pin prompt /adminkey random /generate

    PIN must be at least 8 characters.

  2. Create CSR

    Create a new text file req.inf:

    [NewRequest]
Subject = "CN=myhostnamehere"
Keylength = 2048
Exportable = FALSE
UserProtected = TRUE
MachineKeySet = FALSE
ProviderName = "Microsoft Base Smart Card Crypto Provider"
ProviderType = 1
RequestType = PKCS10
KeyUsage = 0x80

    certreq -new -f req.inf myhostname.csr

    If you get any errors, just reboot and try again with the command that failed.

  3. Get the CSR signed by any Continue reading

Docker Distributed System Summit videos & podcast episodes

Following LinuxCon Europe in Berlin last week, we organized a first of its kind Docker event called Docker Distributed Systems Summit. This two day event was an opportunity for core Docker engineers and Docker experts from the community to learn, collaborate, problem-solve and hack around the next generation of distributed systems in areas such as orchestration, networking, security and storage.

More specifically, the goal of the summit was to dive deep into Docker’s infrastructure plumbing tools and internals: SwarmKit, InfraKit, Hyperkit, Notary, libnetwork, IPVS, Raft, TUF and provide attendees with the working knowledge of how to leverage these tools while building their own systems.

We’re happy to share with you all the videos recordings, slides and audio files available as #dockercast episodes!

Youtube playlist

Podcast playlist

All the slides from the summit are available on the official Docker slideshare account.

Please join us in giving a big shout out to our awesome speakers for creating and presenting the following projects:

  1. InfraKit: A toolkit for creating and managing declarative, self-healing infrastructure
  1. Heart of the SwarmKit: Store, Topology Continue reading

WTF Yahoo/FISA search in kernel?

A surprising detail in the Yahoo/FISA email search scandal is that they do it with a kernel module. I thought I’d write up some (rambling) notes.

What the government was searching for

As described in the previoius blog post, we’ll assume the government is searching for the following string, and possibly other strings like it within emails:

### Begin ASRAR El Mojahedeen v2.0 Encrypted Message ###

I point this out because it’s simple search identifying things. It’s not natural language processing. It’s not searching for phrases like “bomb president”.

Also, it's not AV/spam/childporn processing. Those look at different things. For example, filtering message containing childporn involves calculating a SHA2 hash of email attachments and looking up the hashes in a table of known bad content (or even more in-depth analysis). This is quite different from searching.


The Kernel vs. User Space

Operating systems have two parts, the kernel and user space. The kernel is the operating system proper (e.g. the “Linux kernel”). The software we run is in user space, such as browsers, word processors, games, web servers, databases, GNU utilities [sic], and so on.

The kernel has raw access to the machine, memory, network devices, graphics Continue reading

Technology Short Take #72

Welcome to Technology Short Take #72. Normally, I try to publish these on Fridays, but some personal travel prevented that this time around so I’m publishing on a Monday instead. Enough of that, though…bring on the content! As usual, here’s my random collection of links, articles, and thoughts about various data center technologies.

Networking

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