Category Archives: Security

Shellshock, the Bashdoor Bug – Computerphile – YouTube

Computerphile explains Shellshock

Firejail – A Security Sandbox for Mozilla Firefox

netblue30's avatarl3net - a layer 3 networking blog

We often find ourselves running applications we received in binary format. These include not only traditional software installed on our computers, but also unauthenticated programs received over the network and run in web browsers. Most of the time these applications are too complex to be bug-free, or can come from an adversary trying to get access to our system.

Firejail is a SUID sandbox program that reduces the risk of security breaches by restricting the running environment of untrusted applications. The core technology behind Firejail is Linux Namespaces, a virtualization technology available in Linux kernel. It allows a process and all its descendants to have their own private view of the globally shared kernel resources, such as the network stack, process table, mount table, IPC space.

Introducing Firejail

The program is written in C and only needs libc and POSIX threads (libpthreads), available by default on any Linux platform. The

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How To Check If Your Mac or Linux Machine Is Vulnerable to Shellshock

Copy-paste this line of text into a bash window

env x='() { :;}; echo vulnerable' bash -c 'echo hello'

If the reply comes back as:

vulnerable hello

or

vulnerable
hello

Then your version of bash is vulnerable to shellshock. Most distributions have already pushed out a new version of bash. My Ubuntu machines updated yesterday.

If you use Cygwin, then you need to check there to. Cygwin bash 4.1.10 is definitely vulnerable, but 4.1.11 is not.

If your version of bash is not vulnerable the output will be:

bash: warning: x: ignoring function definition attempt
bash: error importing function definition for `x'
hello

How To Check If Your Mac or Linux Machine Is Vulnerable to Shellshock.

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School dropout codes chat program that foils NSA spying (Wired UK)

The National Security Agency has some of the brightest minds working on its sophisticated surveillance programs, including its metadata collection efforts. But a new chat program designed by a middle-school dropout in his spare time may turn out to be one of the best solutions to thwart those efforts.

School dropout codes chat program that foils NSA spying (Wired UK).

ecryptfs Setup

Some ecryptfs sites for reference, in reference to previous post.

In particular, use of the Private directory is the simplest setup as it encrypts stuff inside a known folder, leaving it in a scrambled state when you are not logged in, so that no-one can get at it.

If you only need access to those files on an occasional basis, then using the mount option is better.

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File-Level Encryption in Linux Using ecryptfs

TrueCrypt Logo

With the NSA spying scandal, all eyes are on ways to stop the surveillance and protect privacy. Campaigns such as Reset the Net have been used to encourage and push sites and people to amp up their security methods. Disasters such as Heartbleed shows what happens if security is compromised, whether intentionally or accidentally

I used to use TrueCrypt to allocate a virtual hard disk and put my private files in that. One of the benefits of this was that TrueCrypt also supported full disk encryption and Plausible Deniability (e.g. hiding an OS within another OS). However, one of the most frustrating parts of TrueCrypt is that you allocate space and any space you do not use is lost. e.g. if you allocate 10GB, but use only 1GB, there is still 9GB left that allocated to the TrueCrypt volume, but cannot be used by the unencrypted space.

Unfortunately, I recently found out that TrueCrypt shut down, under very suspicious and mysterious circumstances. (check the related articles section below). Sure, you could use LUKS instead, or VeraCrypt (but I haven’t tried VeraCrypt), but considering I only want to encrypt a subset of my files, and not the whole partition, that might be a little overkill.

So, I investigated the ecryptfs. Details can be found on the Wikipedia page, but in short, it allows you to mount directories (it comes with a wrapper to the mount command), but unlike other mount wrappers, you are allowed to mount on top of the same directory. In other words, you can do:

sudo mount.ecryptfs ~/SecuredData ~/SecuredData

And this will take the data stored in the directory and transparently decrypt it when you try to access the directory.

If you copy data into the directory, ecrypt will encrypt it and store it in the underlying directory in an encrypted manner. When you unmount the directory, only the encrypted data is visible. If you combine the mounting process with the optional Filename Encryption, then all you see are files with garbled filenames.

ecrypt supports various encryption methods, from AES and Blowfish, to 3DES and Twofish. Obviously, the higher you choose the encryption level, the slower the access. 3DES encryption resulted in a transfer rate of 7MB/s for me, when copying to the encrypted space, and AES was 16MB/s, so balance your requirement of high encryption vs slow access.

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Denial of service attack (part 2) | Building Feedly

Feedly has gone down again, as a result of another DDoS

7:26am PST: We are currently being targeted by a second DDoS attack and are working with our service providers to mitigate the issue.

As with yesterday’s attack, your data is safe. We apologize for the inconvenience and will update this blog post as more information is available or the situation changes.

Denial of service attack (part 2) | Building Feedly.

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Evernote and Feedly Hit by Cyberattacks, Held for Ransom

Feedly is up now, but some sites still haven’t updated their articles yet:

Popular note-taking app Evernote and RSS reader Feedly have been hit with major cyberattacks as hackers demand ransom from the latter site to get it back online.

Both Evernote and Feedly, two services that work together, confirmed they suffered DDoS (distributed denial of service) attacks, a type of cybercrime that kicks sites offline and is meant to disrupt usage (not steal user data). But Feedly, which is still down, detailed in a blog post that hackers are holding the site up for ransom. It’s unknown as of now if the cyber criminals asked for ransom from Evernote too.

Evernote and Feedly Hit by Cyberattacks, Held for Ransom.