A Look at the Buffer-Overflow Hack

Mr. Harari disects the buffer-overflow hack, thereby giving us the necessary information to avoid this problem.
Conclusions

The fact that an application is used all over the Web does not mean it is secure, so take care when installing a new application on your machine. In fact, WWW applications are more likely to be searched deeply for security holes by crackers with bad intent. System administrators should read the security newsgroup and related web pages in order to keep applications known to have security holes off the system and to upgrade them when patches become available. Application programmers should take care to write tight code containing proper checks for array and variable lengths in order to foil this type of hack.

Finally, I would like to briefly mention three other things. One, a kernel patch is available that makes the stack memory area a non-executable one. I have never tested it, since applications do exist which count on the fact that the stack is executable, and these applications will most likely have problems with this patched kernel. Two, a special mode to the Intel processor is available that has the stack grow from the lower memory addresses to the higher memory addresses, thus making a buffer overflow almost impossible. Three, a set of libraries available on some systems helps the programmer write code with no such errors. All the programmer has to do is tell the library functions the assumptions about a variable and these functions will verify that the variable meets the specified criteria.

Eddie Harari works for Sela Systems in Israel as a lecturer and a consultant. He is currently involved in networking security projects and can be reached via e-mail at eddie@sela.co.il.

______________________

Comments

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Question

cha's picture

Do you have any idea for solution at scan parameter of PHP code.
Thank you.

What to do.

Digi String's picture

Nice article, but what to do with the buffer overflow created?

Webinar
One Click, Universal Protection: Implementing Centralized Security Policies on Linux Systems

As Linux continues to play an ever increasing role in corporate data centers and institutions, ensuring the integrity and protection of these systems must be a priority. With 60% of the world's websites and an increasing share of organization's mission-critical workloads running on Linux, failing to stop malware and other advanced threats on Linux can increasingly impact an organization's reputation and bottom line.

Learn More

Sponsored by Bit9

Webinar
Linux Backup and Recovery Webinar

Most companies incorporate backup procedures for critical data, which can be restored quickly if a loss occurs. However, fewer companies are prepared for catastrophic system failures, in which they lose all data, the entire operating system, applications, settings, patches and more, reducing their system(s) to “bare metal.” After all, before data can be restored to a system, there must be a system to restore it to.

In this one hour webinar, learn how to enhance your existing backup strategies for better disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible bare-metal recovery solution for UNIX and Linux systems.

Learn More

Sponsored by Storix