Format string vulnerabilities belong to a special family of vulnerabilities: a family of vulnerabilities that were once destructive but now days receive a decreasing amount of attention. Since most vulnerable code samples are based on poor C/C++ programming education, much like SQL Injections in SQL, most researchers believe that this vulnerability group can be completely mitigated with proper coding standards. However, this blog post will address a hidden aspect of the format string vulnerability, one that can impact quite a large number of high level programming languages.
After a long patching process, CVE 2016-8636 was now fixed and can be publicly disclosed. CVE 2016-8636 is caused by a classic integer-overflow vulnerability, showing that even the linux kernel suffers from this major vulnerability family.
During the end of august I made an audit to the C modules in the popular Python library, version 2.7.12. This audit quickly produced the 1st vulnerability I found in a high-profile library, the 1st of many more that came afterwards.
The C/C++ programing language seems simple and quite straight forward to most common/embedded developers. Unfortunately, most of the programmers lack knowledge of the C standard, resulting in many security vulnerabilities that can be found in those dark shadows of the code. This post will try to introduce a small part of the integer overflow world, and specifically it’s sometimes undefined behavior.