UNIX/Linux as a poor target
UNIX has some characteristics that make it a less attractive target for security attacks. Some of these characteristics are as follows:
- There are many versions and builds.
- Users are generally more expert.
- Scripts are not as easily run (compared with Outlook).
- File ownership limits malware spread.
Many versions and builds
While code and hacks are easily exchanged, specific exploits may not work on a majority of UNIX platforms. For example, a kernel root kit initially developed for Linux 2.4.20-8 on Red Hat may have to be tested and adapted to be useful on other systems, such as Debian. This requires a level of discipline and configuration management that is not normally a trait of the typical troublemaking hacker. As a result, there may be many exploits developed for UNIX, but few of them are universally dangerous.
UNIX has not made great inroads as a popular destop workstation for the masses. It is still primarily used on servers, embedded systems, and software development platforms. All of these uses tend to make the average UNIX user more knowledgeable about the operating system and security. Therefore, if the technical expertise of the average user is greater, attacks against their platforms will, on the whole, be less frequent and harder to accomplish.
Attackers, like most forces, will seek the path of least resistance. Attacking a workstation that is managed by a non-technical person will certainly be easier than attacking one managed by an expert.
Scripts not as easily run
There are many scripting techniques in UNIX. They range from Perl to Bourne shell. However, unlike Windows, the scripting is not tightly integrated into common applications (such as Outlook and Word). In UNIX, scripts can be integrated into applications such as mail and word processing, but it is not the default configuration. This makes UNIX much less vulnerable than a Windows system that is running Outlook and allows users to commonly run powerful Visual Basic scripts.
It is not uncommon for malware to take advantage of commonly run executables to propagate an attack. In these cases, the malware writes itself to a file that is later executed by the unaware user. This kind of attack is made possible because, to perform normal computing functions, restricted users are permitted to run executables that have root or administrator-level access to system resources. This is true for UNIX as well.
Where UNIX has an advantage is in that the file ownership is different than file execution permission. Although a user may be able to run a critical application, they usually do not own the application and therefore would not normally be able to write or alter the executable. The inability of a common user to alter an executable is a severe restriction on viruses and worms that depend on users to propagate their malware.
In this tutorial:
- UNIX and Linux Security
- Network and development tools
- UNIX/Linux as a poor target
- Open source issues
- Detecting hardware changes
- Disk partitioning
- Prepare for the eventual attack
- Controlling the Configuration
- Kernel configurations
- Kernel modules
- proc file system
- Operating UNIX Safely
- Uncommon services
- Processes controlling processes
- The chkconfig command
- Controlling users
- Encryption and certificates
- Hardening UNIX
- Packet filtering with iptables