Libsafe: Transparent System-wide Protection Against Buffer Overflow Attacks

Libsafe is a practical solution that protects against the most common forms of buffer overflow attacks. Such attacks often result in granting the attacker full privileges on the target system. Libsafe is implemented as a shared library that intercepts calls to vulnerable standard library functions. Based on an inspection of the process stack and the function arguments, Libsafe ensures that no return addresses can be overwritten, thus preventing the most common form of buffer overflow attack. Although security concerns encompass a wide range of issues and vulnerabilities, perhaps the most commonly exploited vulnerability is the buffer overflow vulnerability. Advisories issued by leading security organizations include many warnings about buffer overflow problems. Buffer overflows are significant in several ways. First, the most common outcome of a successful attack is a root shell, which is an interactive shell with root privileges. With a root shell, the attacker is able to modify or view files, install back doors, or set up further attacks, such as distributed denial of service attacks. Second, many buffer overflows can be triggered remotely by targeting commonly provided services. Since the attack is carried out at the application level, firewalls are useless in preventing attacks against required services. Third, the proliferation of exploit code permits even unsophisticated attackers to perpetrate buffer overflow attacks. The main problem underlying buffer overflows is bad programming. A common data structure is the buffer or array. When the buffer contains characters, it is called a string. Consider the following example, which contains a buffer overflow vulnerability. char *src = "hello world";