CVE-2005-4418 in util-vserver
Summary
by MITRE
util-vserver before 0.30.208-1 with kernel-patch-vserver before 1.9.5.5 and 2.x before 2.3 for Debian GNU/Linux sets a default policy that trusts unknown capabilities, which could allow local users to conduct unauthorized activities.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability described in CVE-2005-4418 represents a critical security flaw in the util-vserver virtualization framework for Debian GNU/Linux systems. This issue affects versions of util-vserver prior to 0.30.208-1 and kernel-patch-vserver versions before 1.9.5.5 and 2.x versions before 2.3. The core problem lies in the default policy configuration that establishes an overly permissive security model, specifically trusting unknown capabilities without proper validation or restriction mechanisms.
The technical flaw manifests through improper capability management within the virtualization environment, where the system fails to implement adequate security controls for unknown or untrusted capabilities. This design weakness creates a trust model that assumes all capabilities are legitimate and safe, thereby bypassing normal security boundaries that should protect against unauthorized access and privilege escalation. The vulnerability operates at the kernel level through the vserver patch mechanism, which provides virtualization capabilities while maintaining security isolation between virtual environments.
From an operational perspective, this vulnerability enables local users to exploit the trust model and conduct unauthorized activities that would normally be restricted. Attackers can leverage this weakness to escalate privileges, access restricted resources, or perform actions that should be prohibited within the virtualized environment. The impact extends beyond simple privilege escalation as it fundamentally undermines the security isolation that virtualization technologies are designed to provide, potentially allowing attackers to compromise multiple virtual environments or access sensitive system resources.
The vulnerability aligns with CWE-250, which addresses "Execute Code with Unusual or Unconventional Program Execution" and CWE-276, addressing "Insecure Default Permissions," as it involves both improper privilege handling and insecure default configuration settings. From an ATT&CK framework perspective, this vulnerability maps to T1068, "Exploitation for Privilege Escalation," and T1548.001, "Abuse Elevation Control Mechanism," as it allows adversaries to exploit weak privilege control mechanisms to gain elevated access within the virtualized environment.
Mitigation strategies should focus on updating to patched versions of util-vserver and kernel-patch-vserver, specifically implementing versions 0.30.208-1 or later for util-vserver and 1.9.5.5 or later for kernel-patch-vserver. System administrators should also implement strict capability management policies that explicitly define and restrict unknown capabilities, ensuring that the default security model enforces least privilege principles. Additional protective measures include implementing proper monitoring and logging of capability usage, conducting regular security audits of virtualization configurations, and establishing robust access control policies that prevent unauthorized users from exploiting the trust model weakness. Organizations should also consider implementing security frameworks that enforce mandatory access controls and regularly review virtualization security configurations to prevent similar vulnerabilities from arising in other components of their virtualized infrastructure.