Ferry Boender
Programmer, DevOpper, Open Source enthusiast.
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Category: security
How to REALLY test for Bash Shellshock (CVE-2014-6271)
Like always in a crisis, many things go wrong. Everyobody starts chattering, and start deteriorating the signal-to-noise level. I’ll keep this brief. There are a bunch of sites out there that are telling you how to test for the Bash Shellshock vulnerability. Many of the tests are WRONG: # WROOOOOOOOOOOOOOOOONG $ env x=’() { ;;}; […]
16 things you should absolutely configure on any new server
It seems even professional sysadmins occasionally forgets the bare minimum configuration that should be done on a new machine. As a developer and part-time system administrator, I can’t count the number of times I’ve had to waste significantly more time Here’s a, by no means exhaustive, list of things you should configure on any new […]
Re-use existing SSH agent (cygwin et al)
(Please note that this post is not specific to Windows nor Cygwin; it'll work on a remote unix machine just as well) On my netbook, I use Windows XP in combination with Cygwin (A unix environment for Windows) and Mintty for my Unixy needs. From there, I usually SSH to some unix-like machine somewhere, so […]
Stop Pingback/Trackback Spam on WordPress
I guess the spammers finally found my blog, cause I’ve been getting a lot of pignback/trackback spam. I tried some anti-spam plugins, but none really worked, so I disabled pingbacks altogether. Here’s how: First, log into wordpress as an admin. Go to Settings → Discussion, and uncheck the Allow link notifications from other blogs (pingbacks […]
SSH Tips and Tricks
(The lastest version of this article is always available in stand-alone HTML format and in PDF format. The original AsciiDoc source is also available. Please link to the HTML version, not this Blog post!) SSH is capable of more than you’d think! This article describes some of the lesser known features and configuration options. It […]
Regular expression Denial of Service (ReDoS)
It’s only logical, but I hadn’t really thought about it much. Turns out Regular Expression can be vulnerable to external Denial of Service attacks.
Security Questions considered harmful
Many online services allow, or even worse, require, the so called “Security Question”. It is a question/answer you can enter in case you ever forget your password or can’t access your account for some reason. In my opinion, security questions are an incredibly bad idea, from a security perspective. The usual security questions are things […]
chkrootkit false positives filtering
Chkrootkit is a tool that searches for rootkits, trojans and other signs of break-ins on your system. Like most security scanners, it sometimes generates false positives. Chkrootkit doesn’t have a native way to filter those out. From the FAQ: [Q:] chkrootkit is reporting some files and dirs as suspicious: `.packlist’, `.cvsignore’, etc. These are clearly […]
SSH + SOCKS5 = Universal proxy
I didn’t know it, but (Open)SSH supports setting up a Socks5 proxy: -D [bind_address:]port Specifies a local “dynamic” application-level port forwarding. This works by allocating a socket to listen to port on the local side, optionally bound to the specified bind_address. Whenever a connection is made to this port, the connection is forwarded over the […]
Virtualization Security
Theo de Raadt on virtualisation security: > Virtualization seems to have a lot of security benefits. You’ve been smoking something really mind altering, and I think you should share it. x86 virtualization is about basically placing another nearly full kernel, full of new bugs, on top of a nasty x86 architecture which barely has correct […]
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