A critical vulnerability (CVE-2013-6629) was discovered in the get_sos function in jdmarker.c, affecting (1) libjpeg 6b and (2) libjpeg-turbo through 1.3.. This security flaw is present in widely used products, such as Google Chrome before version 31..165.48, Ghostscript, and other applications that implement the affected JPEG libraries. The vulnerability allows remote attackers to extract sensitive information from uninitialized memory locations via a specially crafted JPEG image. This post will dive into the details of this security issue, provide code snippets that demonstrate the vulnerability, and explore how you can protect your applications from this exploit.

Code Snippet

The heart of the problem lies within the get_sos() function in the jdmarker.c file, which is responsible for processing segments that follow the Start Of Scan (SOS) JPEG markers.

for (ci = ; ci < cinfo->comps_in_scan; ci++) {
  ...
  /* Make sure requested component is in this scan */
  for (coefi = ; coefi < num_components; coefi++) {
    if (cinfo->cur_comp_info[coefi]->component_id == component_id)
     (cid:image001.png@01D1C197.001E88E)
      break;
  }
  if (coefi >= num_components)
    ERREXIT4(cinfo, JERR_BAD_SCAN, msg, ", component ");
  compptr->dc_tbl_no = GET_BITS(4);
  ...
}

In the code above, the function iterates over all components in the scan and fails to check for duplicated component data properly. As a result, an attacker can exploit this issue by crafting a malicious JPEG image that contains duplicate component information.

Exploit Details

The exploit abuses the insufficient check for duplicated component data to access uninitialized memory locations. This access allows remote hackers to extract sensitive information such as passwords, user data, and other confidential material from memory. This security issue poses a significant threat to privacy, confidentiality, and the overall security of affected systems.

1. NVD - CVE-2013-6629
2. SecurityFocus - Bugtraq ID: 62441
3. Google Chrome Releases Blog
4. Libjpeg-turbo Security

How to Protect Your Applications

Users of the affected library versions (libjpeg 6b and libjpeg-turbo through 1.3.) should upgrade their software as soon as possible. Google Chrome users can protect themselves by updating their browser to version 31..165.48 or later, which contains a fix for this vulnerability.

Moreover, application developers should carefully analyze their systems to ensure that no traces of the vulnerable libraries are in use. Patches and updates are available to address this vulnerability, and it is critical to apply them as soon as possible to prevent potential attacks.

Conclusion

The CVE-2013-6629 vulnerability demonstrates the dangers of skipping proper checks in software code, leading to severe security risks to both user data and system integrity. In this case, the lack of duplication checks within the get_sos() function of widely-used JPEG libraries enabled attackers to access sensitive information from uninitialized memory locations, leading to serious consequences in privacy and security. By staying up-to-date with the latest patches and updates, users and developers can work together to protect themselves against potential attacks targeting this vulnerability.

Timeline

Published on: 11/19/2013 04:50:56 UTC
Last modified on: 06/21/2023 18:19:38 UTC