Linux Kernel NFS41+ Subsystem Use-after-Free vulnerability [CVE-2018-16884]

CVE number – CVE-2018-16884

A vulnerability in the NFS41+ subsystem of the Linux Kernel could allow an authenticated, adjacent attacker to cause a denial of service (DoS) condition or execute arbitrary code on a targeted system.The vulnerability exists because the bc_svc_process() function of the affected software uses the wrong back-channel ID.

An attacker with access to a malicious container could exploit this vulnerability by submitting malicious input to the targeted system. A successful exploit could cause a use-after-free condition, which could allow the attacker to execute arbitrary code or cause a DoS condition on the targeted system. Kernel.org has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, the attacker must be on the same physical or logical network to submit malicious input to a targeted system, making exploitation more difficult in environments that restrict network access from untrusted sources.

Safeguards

• Administrators are advised to apply the appropriate updates.
  
  Administrators are advised to allow only trusted users to have network access.
  
  Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.
  
  Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
  
  Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
  
  Administrators are advised to monitor affected systems.

Vendor Announcements

• Kernel.org has released a bug report at the following link: use-after-free in svc_process_common()

Fixed Software

• Kernel.org released a software patch at the following link: nfs: use-after-free in svc_process_common()