👉 Overview
👀 What ?
Linux ld.so privilege escalation exploit is a security vulnerability that manipulates the dynamic linker/loader ld.so of the Linux operating system to escalate privileges from a normal user to root user.
🧐 Why ?
Understanding this exploit is crucial because it sheds light on how certain system vulnerabilities can be exploited to gain unauthorized access or privileges. This knowledge is essential for system administrators, security professionals and ethical hackers to secure their systems.
⛏️ How ?
The exploit involves tricking the linker/loader ld.so into executing a malicious library or a script. This can be achieved by setting the LD_PRELOAD environment variable to point to the malicious library or script. Once the system runs a binary that requires the ld.so, it will also execute the malicious script, potentially with escalated privileges.
⏳ When ?
The use of Linux ld.so privilege escalation exploit began to be noticed in the early 2000s. However, its popularity among hackers has grown over the years due to the ubiquity of Linux systems and the relative simplicity of the exploit.
⚙️ Technical Explanations
In a Linux system, ld.so is a dynamic linker/loader that loads the shared libraries needed by a program into the memory space of the program at run time. It's possible for a malicious user to manipulate this process by creating a malicious shared library and using the LD_PRELOAD environment variable to force the linker/loader to load this library before any other. The malicious library can contain functions that are also found in other libraries used by the program. Since ld.so loads the libraries in the order specified by LD_PRELOAD, the malicious functions will take precedence over the legitimate ones. This can lead to arbitrary code execution with the privileges of the user running the program. If the program is running with root privileges, this can lead to a full system compromise.