How to use the command 'checksec' (with examples)

The checksec command is a powerful tool used to examine security properties and features of binary executables, running processes, and the Linux kernel. By leveraging these insights, developers and system administrators can assess the security posture of their systems and applications, ensuring they adhere to modern security standards and practices. checksec can reveal information about security mechanisms such as Address Space Layout Randomization (ASLR), Stack Canaries, and more, helping in identifying potential vulnerabilities before they can be exploited.

Use case 1: List security properties of an executable binary file

Code:

checksec --file=path/to/binary

Motivation:

Understanding the security properties of an individual binary file is crucial when evaluating the software’s resilience against particular types of attacks. For example, if a developer is tasked with enhancing the security of an application, they can use checksec to check if features like ASLR or DEP (Data Execution Prevention) are enabled, which help in preventing exploits that rely on predictable memory addresses or the execution of non-code segments.

Explanation:

• --file=path/to/binary: This option specifies the path to the executable binary file whose security properties you wish to examine. Replacing path/to/binary with the actual path of the target binary allows checksec to analyze that specific file for its security features.

Example output:

RELRO           STACK CANARY      NX            PIE                 RPATH      RUNPATH      FILE
Partial RELRO   Canary found      NX enabled    PIE enabled         No RPATH   No RUNPATH   /path/to/binary

Use case 2: List security properties recursively of all executable files in a directory

Code:

checksec --dir=path/to/directory

Motivation:

Analyzing all executables within a directory is useful when performing a comprehensive audit of a software package or a collection of programs. This can be particularly useful in development environments or situations where software from various sources is being integrated. By examining each executable, developers can ensure a consistent security posture across an entire suite of applications.

Explanation:

• --dir=path/to/directory: This option directs checksec to scan all executable files within the specified directory path. Replacing path/to/directory with the actual directory lets checksec evaluate each executable file and report on their security features recursively.

Example output:

RELRO           STACK CANARY      NX            PIE                 RPATH      RUNPATH      FILE
Partial RELRO   Canary found      NX enabled    PIE enabled         No RPATH   No RUNPATH   /path/to/directory/file1
Full RELRO      Canary found      NX enabled    PIE enabled         No RPATH   No RUNPATH   /path/to/directory/file2
...

Use case 3: List security properties of a process

Code:

checksec --proc=pid

Motivation:

Examining the security properties of a running process is valuable for system administrators and cybersecurity professionals aiming to assess the runtime security configurations of applications. This is especially critical in environments where processes handle sensitive data or perform critical operations, as runtime security mechanisms significantly impact the application’s resistance to exploitation.

Explanation:

• --proc=pid: This option specifies the process ID (PID) of the running process whose security features you want to analyze. By providing the appropriate PID, checksec can assess how the process utilizes security features at runtime, giving insights into its potential attack surface.

Example output:

RELRO           STACK CANARY      NX            PIE                 RPATH      RUNPATH      FILE
Full RELRO      No canary         NX enabled    PIE enabled         No RPATH   No RUNPATH   /usr/bin/some_process

Use case 4: List security properties of the running kernel

Code:

checksec --kernel

Motivation:

Inspecting the security properties of the running kernel helps in determining the overall security framework of the operating system. Kernel-level security features can mitigate various classes of vulnerabilities, so understanding which features are enabled is essential for system hardening purposes. Administrators can use this information to take necessary actions to improve the security of the kernel and, consequently, the entire system.

Explanation:

• --kernel: This flag instructs checksec to display the security features currently in effect for the running Linux kernel. By invoking checksec with this option, users gain a high-level overview of the kernel’s security capabilities, essential for maintaining a secure operating environment.

Example output:

Kernel protections:  partial ret2usr guard   CONFIG_GRKERNSEC     KERNEXEC     UDEREF     NX      TPE      

Conclusion

The checksec command serves as an invaluable asset for those focused on enhancing security on Linux systems. Each use case—from scrutinizing a single binary to evaluating the kernel itself—provides insights into potential weaknesses and confirms the efficacy of implemented security measures. By incorporating checksec into regular security assessments, developers and system administrators can significantly bolster their defensive strategies against various threats.