If you are being attacked or abused by a particular host, just enter the following command to deny all access to the host: /sbin/route add -host <ip address> reject Replace with the IP address of the host you want to block. The address will stay blocked until you bounce the interface. Alternatively, you could allow […]

Check out the European Institute for Computer Anti-Virus Research (eicar) Anti-Virus Test File page. EICAR provides test files you can send to your users to determine if their anti-virus software is functioning correctly. We’ve seen this work fine on Trend Micro and Norton Anti-Virus software, but most ant-virus software should correctly detect these files. To […]

If you have any kind of intrusion detection set up like Psionic’s PortSentry or a personal firewall, you’ll see attempts to connect on ports you may not be familiar with. Even looking up the port in /etc/services doesn’t tell the whole story. To find all known network services, trojans, worms and exploits associated with a […]

We wrote about blocking particular IP addresses with the route command here. If you are already using iptables, or want to start, a better way is to block particular hosts: iptables -I INPUT -s 25.55.55.55 -j DROP This command will simply drop any packet coming from the address 25.55.55.55. To list the chains: iptables -L […]

Conventional encryption is where there are no keys involved. This can be done with the -c option on GnuPG. When you use this option you will be asked for a passphrase. To decrypt the file the same passphrase is needed. This is ideal for password lists, where you have the ability to share the passphrase […]

One key to check on Windows boxen is the Run key. The run key is located in HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run. When a user logs on, the programs specified in the run key also run. Many times a trojan will install itself here. A lesser evil is the hordes of small little apps that like to run some […]

When I was a kid in 1975, my dad brought home a terminal with an accoustical coupler on the top where I could put a standard phone handset in, and communicate with a Microdata minicomputer at his work. [Dick Pick developed the operating system for the Microdata. To make it fast, he programmed it using […]

There is a most fabulous utility available for free download from Shavlik Technologies here that will scan your Windows boxen for needed security/bug fixes. The command line version doesn’t require registration, and is quite easy to use. The cool thing is that the status of current patches is downloaded at run time. Let’s run this […]

Yet another worm making the rounds via email. This one has a nasty payload. More info here. Removal tool here. Additional info for administrators and operators on IRC networks here.

As moon-howling, tree-hugging, packet-sniffing pagans, we like to celebrate the Summer Solstice by doing a security audit of the systems on our network. Spending the longest day of the year auditing systems will help us avoid spending the longest night of the year restoring a hacked one. In our audit, we will be disabling unused […]

There was a time, not so very long ago, when we used to enjoy running an ftp server and locking our users into tiny little chrooted jails. While we still enjoy denying users their freedom, we now prefer to do so using a maximum security facility. The sftp file transfer program, which comes with OpenSSH […]

Microsoft has published a tool available here that will tell you what hosts need patching to protect against the 823980 buffer overrun in RPC flaw (Blaster).

There is a new bagle worm that uses an exploit in IE. It does not need to have the user open an attachment, they just need to read an email with HTML in it. !!! There is a test to see if you are vulnerable here: http://secunia.com/MS03-032 More detailed info here: href=http://secunia.com/advisories/9580/ Bagle Q info […]

We use MD5deep, because it has a recursive option which we discuss in this article. For now, though, we are just going to cover how to verify the MD5 checksum on a file. Grab the MD5 checksum from a site authoritative for your software package, and grab the software from a mirror site. Of course, […]

We talked a little about MD5deep in this article. One nice thing about MD5deep is that it can do recursion. This allows you to create a set of MD5 sums for an entire directory. /etc is a good one to use as an example. Let’s create the set of MD5 sums: root@srv-1 etc # md5deep […]

This is certainly an old topic, but I always forget how to compile PGP 2.6.2 on GNU/Linux. Grab the source from MIT, probably, is what you want. You may also want to consider gpg. Much has changed since 1994! PGP 2.6.2 is particularly interesting for keeping password files using conventional encryption. It is possible to […]

There is a local user privilege exploit for the Linux kernel. Details are here: http://isec.pl/vulnerabilities/isec-0021-uselib.txt One thing to remember is that a local user does not mean that the user has to have access to the physical machine. It means that any user that can run code on the machine can gain root access.

If you need to automate FTP downloads, and want lots of flexibility, an oldie but goodie is Kermit. I know what you’re thinking: “Hey, isn’t Kermit an old DOS comms program?”. Yes, it is a very old program. The cool thing about this, though, is that if you need to automate file transfers, it has […]