CVE-2021-28153 is a medium-severity vulnerability discovered in GNOME GLib versions prior to 2.66.8. The vulnerability arises when the function g_file_replace() is employed with the G_FILE_CREATE_REPLACE_DESTINATION flag to replace a path that is a dangling symlink. This action incorrectly creates the target of the symlink as an empty file, which could have security implications if the symlink is controlled by an attacker. Importantly, if the path points to a symlink of an existing file, the contents of that file remain unchanged.
The vulnerability has a CVSS score of 5.3, indicating a medium risk level. The attack vector is classified as network-based, with low complexity and no privileges required. Organizations should be particularly attentive to this vulnerability, as the potential for exploitation exists given that it affects systems that rely on GNOME GLib.
Risk to organizations includes the possibility of unauthorized file creation, which may lead to further exploitation or data integrity issues. Organizations using affected versions of GNOME GLib should prioritize remediation to mitigate potential risks.
Given the nature of this vulnerability and its implications, organizations should address it in their priority patch cycle. The urgency for defenders cannot be overstated, as timely response is critical in preventing potential exploitation.
Vulnerability Details
The official CVE description states: 'An issue was discovered in GNOME GLib before 2.66.8. When g_file_replace() is used with G_FILE_CREATE_REPLACE_DESTINATION to replace a path that is a dangling symlink, it incorrectly also creates the target of the symlink as an empty file, which could conceivably have security relevance if the symlink is attacker-controlled.' This vulnerability is categorized under CWE-59, which pertains to the exposure of critical resources through symbolic links.
The CVSS score of 5.3 is indicative of a medium severity level. The integrity impact is classified as low, meaning that while the exploit could alter data, it does not affect the confidentiality or availability of the system.
The vulnerability affects several products, including GNOME GLib, Brocade Fabric Operating System Firmware, Debian Linux, and Fedora. The exposure of systems running these products may lead to the unintended creation of files that could be exploited if not patched.
Technical Analysis
The root cause of CVE-2021-28153 lies in the handling of symlinks by the g_file_replace() function within GNOME GLib. When a symlink that points to a non-existent target (dangling symlink) is replaced, the function incorrectly creates a new empty file at the target location. This behavior poses risks if the symlink is controlled by an attacker.
The attack vector is network-based, allowing potential exploitation from remote locations. The attack complexity is low, requiring no special privileges or user interaction, making it relatively easy for attackers to leverage this vulnerability if they can create or control symlinks on the affected systems.
In terms of impact, the vulnerability affects the integrity of the system by allowing for the creation of files that could lead to unwanted modifications or serve as a foothold for further attacks. However, it does not impact confidentiality or availability.
Risk & Impact Analysis
Organizations utilizing affected systems face significant risks. The ability for attackers to create empty files from dangling symlinks can lead to unauthorized access and manipulation of critical resources. This could potentially compromise the integrity of applications relying on GNOME GLib.
The breadth of impact depends on the deployment environment. In systems where GNOME GLib is widely used, the likelihood of exploitation increases. The urgency for remediation is underscored by the fact that this vulnerability affects multiple platforms and distributions, including Debian and Fedora.
Given the CVSS score of 5.3 and the absence from the KEV catalog, organizations should assess their risk posture and prioritize patching this vulnerability to mitigate potential exploitation. The overall risk level is moderate, requiring prompt action.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of GNOME GLib are affected by CVE-2021-28153: all versions prior to 2.66.8. This includes various distributions such as Debian Linux (version 9.0), Fedora (version 33), and Brocade Fabric Operating System Firmware.
Mitigation & Remediation
Organizations should implement patches for GNOME GLib to version 2.66.8 or higher to remediate this vulnerability. If a patch is unavailable, workarounds may include avoiding the use of g_file_replace() with dangling symlinks.
Additionally, configuration hardening practices should be applied to restrict symlink creation where possible. Organizations may also consider implementing network controls to monitor for suspicious file creation activities.
Monitoring should focus on log indicators related to file creation and modifications within critical directories.
For further assistance, organizations may engage in penetration testing to validate their defenses and identify any potential weaknesses.
Detection Guidance
Organizations should monitor logs for indicators of unusual file activity, particularly in directories where symlinks are frequently utilized. Behavioral anomalies should be investigated, especially those indicating unexpected file creations or modifications.
Network signatures may also be established to detect potential exploitation attempts that leverage this vulnerability. Additionally, any changes to system files or unexpected behavior in applications using GNOME GLib should be closely observed.
AppSecure Threat Intelligence Insight
CVE-2021-28153 highlights critical lessons for security teams regarding the handling of symlinks in software applications. This vulnerability exemplifies how improper handling of file operations can lead to unintended security risks.
Organizations should ensure that their development teams adhere to secure coding practices, particularly when dealing with symbolic links and file manipulation functions. The potential for exploitation is exacerbated in environments where symlinks are commonly used, thus requiring heightened awareness and preventive measures.
To further enhance security posture, organizations can implement a penetration testing methodology and continuous security assessments to identify and remediate vulnerabilities proactively.
Engaging in a comprehensive vulnerability management program can further assist in maintaining a secure environment.
Lastly, organizations should stay updated on security advisories and implement timely patches to mitigate vulnerabilities as they are disclosed.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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