CVE-2020-11446 in ESET
Summary
by MITRE
ESET Antivirus and Antispyware Module module 1553 through 1560 allows a user with limited access rights to create hard links in some ESET directories and then force the product to write through these links into files that would normally not be write-able by the user, thus achieving privilege escalation.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 10/14/2020
The vulnerability identified as CVE-2020-11446 resides within the ESET Antivirus and Antispyware Module versions 1553 through 1560, presenting a critical privilege escalation risk that exploits improper access controls and file system handling mechanisms. This flaw enables attackers with minimal system privileges to manipulate hard link creation within specific ESET directories, subsequently leveraging this capability to write data into files that should normally be protected from modification by unprivileged users. The vulnerability represents a significant security weakness that directly violates fundamental principles of access control and privilege separation.
The technical implementation of this vulnerability stems from inadequate validation of file system operations within the ESET security module. When the antivirus software processes certain file operations, it fails to properly verify the integrity of hard links that may have been created by unprivileged users in protected directories. This oversight allows the malicious user to establish hard links pointing to sensitive system files or configuration resources that typically require elevated privileges to modify. The module's failure to detect or prevent such link manipulation creates a pathway for privilege escalation attacks that can potentially compromise the entire system security posture.
The operational impact of CVE-2020-11446 extends beyond simple privilege escalation, as it provides attackers with the capability to manipulate critical system components through the ESET security infrastructure itself. An attacker can create hard links to system binaries, configuration files, or registry-related resources and then force the antivirus module to write malicious content through these links, effectively bypassing normal file system permissions. This technique can be particularly dangerous when combined with other attack vectors, as it allows adversaries to modify security-critical components without requiring direct administrative access to the system. The vulnerability affects the core security model of ESET products and undermines the trust model that users place in antivirus software to protect system integrity.
This vulnerability maps directly to CWE-276, which describes improper file permissions and inadequate access control mechanisms. The flaw demonstrates a clear violation of the principle of least privilege and represents a classic example of a privilege escalation vulnerability that can be exploited through file system manipulation. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1068 (Exploitation for Privilege Escalation) and T1548.001 (Abuse Elevation Control Mechanism), as it allows attackers to bypass existing privilege control mechanisms through legitimate software functionality. The attack pattern follows a common methodology where adversaries leverage legitimate system tools and processes to achieve unauthorized access, making detection more challenging.
Mitigation strategies for CVE-2020-11446 require immediate patching of affected ESET modules to version 1561 or later, which contains the necessary fixes to prevent unauthorized hard link creation and manipulation within protected directories. System administrators should also implement additional monitoring controls to detect unusual hard link creation patterns in ESET-related directories, as well as review and tighten file system permissions for critical security components. Organizations should consider implementing additional security controls such as mandatory access controls, file integrity monitoring, and privileged access management solutions to reduce the attack surface. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other security software components and ensure comprehensive protection against privilege escalation attacks.