CVE-2017-9811 in Kaspersky
Summary
by MITRE
The kluser is able to interact with the kav4fs-control binary in Kaspersky Anti-Virus for Linux File Server before Maintenance Pack 2 Critical Fix 4 (version 8.0.4.312). By abusing the quarantine read and write operations, it is possible to elevate the privileges to root.
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability identified as CVE-2017-9811 represents a critical privilege escalation flaw within Kaspersky Anti-Virus for Linux File Server software. This issue affects versions prior to Maintenance Pack 2 Critical Fix 4, specifically version 8.0.4.312, where the kernel-level component kav4fs-control binary exhibits improper access controls that allow unprivileged users to manipulate quarantine operations. The vulnerability stems from insufficient privilege separation between user-level processes and kernel-level system components, creating an attack surface that can be exploited by malicious actors to gain root-level system access.
The technical flaw manifests through the manipulation of quarantine read and write operations within the kav4fs-control binary. This binary serves as a critical interface between the user-space application and the kernel-space file system filter driver, where it handles various security operations including file quarantine functions. The vulnerability occurs when the system fails to properly validate user permissions during quarantine operations, allowing a local user to craft specific inputs that trigger unintended behavior within the kernel module. This improper validation creates a path where user-level privileges can be escalated to the highest system privileges, effectively bypassing the standard Linux privilege model and granting complete system control.
The operational impact of this vulnerability is severe and far-reaching, as it provides an attacker with complete system compromise without requiring any special privileges or external attack vectors. Once exploited, the privilege escalation allows for arbitrary code execution at kernel level, enabling attackers to modify system files, install backdoors, exfiltrate sensitive data, or completely disable security controls. The attack requires only local access to the system, making it particularly dangerous in environments where user accounts may be compromised through social engineering, credential theft, or other means. The vulnerability essentially transforms any user account into a root-level administrative account, undermining the fundamental security model of the Linux operating system and the protection mechanisms provided by the anti-virus solution itself.
The exploitability of this vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under privilege escalation techniques, specifically targeting kernel-level privilege escalation methods that leverage insecure file operations and improper access controls. This vulnerability is categorized as a CWE-276: Incorrect Permission Assignment for Critical Resources, which directly relates to the improper privilege handling within the kav4fs-control binary. Organizations using affected Kaspersky Anti-Virus for Linux File Server versions face significant risk exposure, as the vulnerability can be exploited by both malicious insiders and external attackers who have gained initial access to the system. The recommended mitigations include immediate application of the vendor-provided patch, implementation of network segmentation to limit local access, and continuous monitoring for suspicious privilege escalation activities. System administrators should also consider implementing additional security controls such as mandatory access controls and privilege monitoring to detect and prevent exploitation attempts. The vulnerability highlights the critical importance of proper privilege separation in security software and demonstrates how defensive mechanisms can themselves become attack vectors when not properly designed and validated.