etbe

Archive for the 'Security' Category

27 Jun

Kernel Security vs Uptime

For best system security you want to apply kernel security patches ASAP. For an attacker gaining root access to a machine is often a two step process, the first step is to exploit a weakness in a non-root daemon or take over a user account, the second step is to compromise the kernel to [...]

06 Jun

SE Linux Support in GPG

In May 2002 I had an idea for securing access to GNUPG [1]. What I did was to write SE Linux policy to only permit the gpg program to access the secret key (and other files in ~/.gnupg). This meant that the most trivial ways of stealing the secret key would be prevented. [...]

24 May

IPSEC is Pain

I’ve been trying to get ipsec to work correctly as a basic VPN between two CentOS 5 systems. I set up the ipsec devices according to the IPSEC section of the RHEL4 security guide [1] (which is the latest documentation available and it seems that nothing has changed since). The documentation is quite [...]

21 May

Security Flaws in Free Software

I just wrote about the system administration issues related to the recent Debian SSL/SSH security flaw [1]. The next thing we need to consider is how we can change things to reduce the incidence of such problems.
The problem we just had was due to the most important part of the entropy supply for the [...]

18 May

Debian SSH Problems

It has recently been announced that Debian had a serious bug in the OpenSSL code [1], the most visible affect of this is compromising SSH keys - but it can also affect VPN and HTTPS keys. Erich Schubert was one of the first people to point out the true horror of the problem, only [...]

03 Apr

Trust and My SE Linux Play Machine

When discussing the machine there are two common comments I get. One is a suggestion that I am putting myself at risk, I think that the risk of visiting random web sites is significantly greater. Another is a challenge to put the machine on my internal network if I really trust SE Linux, as noted I have made mistakes in the past and there have been Linux kernel bugs - but apart from that it’s always best to have multiple layers of protection.

02 Apr

SE Linux Play Machine and Passwords

My SE Linux Play Machine has been online again since the 18th of March.

On Monday the 11th of Feb I took it offline after a user managed to change the password for my own account. Part of the problem was the way /bin/passwd determines whether it should change a password.

02 Apr

SE Linux Etch Repository for AMD64

My Etch back-port repository of SE Linux related packages (which I documented in a previous post) now has a complete set of packages for AMD64. From now on I aim to make AMD64 and i386 be my main supported platforms for SE Linux development.

28 Mar

Debian SE Linux Status

At the moment I’ve got more time to work on these things than I have had for a while.
I’ve got Etch support going quite well (see my post about my Etch repository [1]), the next step is to back-port some packages for AMD64 to get it working as well as i386.
I’ve got an i386 Xen [...]

26 Feb

Chilled Memory Attacks

In 1996 Peter Gutmann wrote a paper titled “Secure Deletion of Data from Magnetic and Solid-State Memory” [1]. In that paper he mentions the fact that the contents of RAM last longer at lower temperatures and suggests that data could be retained for weeks at a temperature of -60C or lower (while 140C causes [...]

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