Researchers recently discovered a security vulnerability (CVE-2020-19726) in the binary utility software package binutils, affecting the library libbfd.c version 2.36. This vulnerability allows attackers to read or write to system memory or initiate a denial of service (DoS) attack. In this article, we'll take a closer look at the vulnerability, the affected code, and steps to mitigate this exploit risk.

Vulnerability Details

CVE-2020-19726 occurs within the Binary File Descriptor library (libbfd) of binutils, which is widely used by developers to build, analyze and manipulate binary files. The vulnerability specifically occurs in the handling of auxiliary symbol data, a vital part of binary files that stores extra information about functions, variables, or files.

The affected code snippet can be found in the libbfd.c file, version 2.36

/* Read in the external_syms.  */
 if (priv->external_syms == NULL)
    file_ptr pos;

    pos = obj_sym_filepos (abfd);
    if (bfd_seek (abfd, pos, SEEK_SET) != 
    || (bfd_bread (& priv->external_syms[], priv->localsymsize,
                               abfd) != priv->localsymsize)
    || (bfd_bread (& priv->external_syms[1], priv->extsymssize,
                               abfd) != priv->extsymssize))
            return NULL;

The problem arises when an attacker can trigger a read or write operation beyond the allocated system memory due to improper handling of the auxiliary symbol data. As a consequence, attackers can potentially leak sensitive information, corrupt memory data, or cause a DoS attack.

Original References

1. CVE Details - CVE-2020-19726
2. Binutils Git Repository - binutils 2.36
3. Bug Report - Bug 24960

Exploit Details

While there are currently no publicly available exploit codes, the possibility exists for skilled attackers to craft a custom exploit that leverages the vulnerability. To create a successful exploit, an attacker needs to find a way to manipulate the auxiliary symbol data in a binary file in a manner that triggers the read or write operation beyond allocated memory.

Mitigation Steps

To protect your systems against potential exploits leveraging CVE-2020-19726, follow these security best practices:

1. Update to the latest version of binutils: The issue has been addressed in the latest version of binutils. Therefore, it is essential to keep your binutils installation up-to-date to minimize the risk of attack.

2. Apply patches and security updates: Regularly check the vendor's website and security mailing lists for any patches, security updates, or important announcements related to binutils. Apply these updates promptly to protect your system and software.

3. Review and restrict access to binary files: Limit the access and execution of sensitive binary files to a limited set of trusted users or system administrators. Implement proper access controls and privilege escalations on relevant files to prevent unauthorized access.

4. Monitor system logs for unusual activity: Periodically review system logs and monitor for any suspicious activity, such as attempts to read or write to memory beyond the allocated boundaries, or repeated crashes caused by DoS attacks.

5. Create and test incident response plans: Develop a robust incident response plan for managing potential exploits and security breaches. Regularly test and update the plan to ensure its effectiveness in the face of evolving attacks.

In conclusion, the CVE-2020-19726 vulnerability in binutils libbfd.c 2.36 could have severe implications for affected systems, as it allows attackers to read or write to system memory or cause a denial of service. It is imperative to keep your software updated and follow security best practices to mitigate the potential risks associated with this vulnerability.


Published on: 08/22/2023 19:16:00 UTC
Last modified on: 08/25/2023 02:46:00 UTC