CVE-2021-3554 in Endpoint Security Tools
Summary
by MITRE • 11/24/2021
Improper Access Control vulnerability in the patchesUpdate API as implemented in Bitdefender Endpoint Security Tools for Linux as a relay role allows an attacker to manipulate the remote address used for pulling patches. This issue affects: Bitdefender Endpoint Security Tools for Linux versions prior to 6.6.27.390; versions prior to 7.1.2.33. Bitdefender Unified Endpoint versions prior to 6.2.21.160. Bitdefender GravityZone versions prior to 6.24.1-1.
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Analysis
by VulDB Data Team • 11/27/2021
The CVE-2021-3554 vulnerability represents a critical improper access control flaw within the patchesUpdate API implementation of Bitdefender Endpoint Security Tools for Linux operating in relay mode. This vulnerability specifically targets the authentication and authorization mechanisms that govern how patch update requests are processed and validated. The flaw allows malicious actors to manipulate the remote address used for pulling patches, effectively bypassing intended security controls that should prevent unauthorized modification of update sources. The vulnerability affects multiple Bitdefender product lines including Endpoint Security Tools for Linux, Unified Endpoint, and GravityZone versions prior to their respective secure releases, indicating a widespread impact across the vendor's security portfolio.
The technical implementation of this vulnerability stems from insufficient validation of remote addresses within the patch update relay functionality. When the system processes patch update requests, it fails to properly verify the authenticity and integrity of the remote address being used for patch retrieval. This weakness enables attackers to redirect patch downloads to malicious servers or compromised endpoints, potentially allowing for the injection of malicious code or the execution of man-in-the-middle attacks against the update process. The vulnerability operates at the application layer and specifically affects the API endpoint responsible for handling patch distribution, making it particularly dangerous as it can compromise the integrity of security updates that are meant to protect systems from known threats.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential compromise of entire security infrastructures. Attackers exploiting this flaw could deliver malicious patches that contain backdoors, rootkits, or other persistent threats that would be executed with the privileges of the security agent. The relay role functionality, which is designed to forward patch requests through intermediate servers, becomes a critical attack vector when the remote address validation is bypassed. This vulnerability particularly threatens environments where patch management is centralized and relies on automated update mechanisms, as it allows attackers to subvert the security update process itself. The impact is exacerbated by the fact that security updates are typically considered trusted components, making this vulnerability a prime target for attackers seeking to establish persistent presence within networks.
Mitigation strategies for CVE-2021-3554 should prioritize immediate deployment of the vendor-provided patches and updates for all affected versions of Bitdefender products. Organizations should implement network segmentation and firewall rules to restrict access to the patchesUpdate API endpoints, limiting the attack surface and preventing unauthorized access. The implementation of strict API authentication and authorization controls, including the use of secure tokens and certificate-based authentication, should be enforced to prevent unauthorized manipulation of update parameters. Additionally, organizations should conduct comprehensive network monitoring to detect any suspicious traffic patterns or attempts to redirect patch update requests. The vulnerability aligns with CWE-284, which addresses improper access control, and can be mapped to ATT&CK technique T1027 for modification of executables and T1554 for compromisation of update systems. Regular security assessments and vulnerability scanning should be implemented to identify similar access control weaknesses in other security tools and systems within the organization's infrastructure.