Nokogiri Ruby Kernel.open Method Command Injection Vulnerability [CVE-2019-5477]

CVE number – CVE-2019-5477

A vulnerability in Nokogiri could allow an unauthenticated, remote attacker to inject and execute arbitrary commands on a targeted system.

The vulnerability exists in certain situations when the Nokogiri::CSS::Tokenizer#load_fileundocumented method is being passed untrusted user-supplied input. An attacker could exploit this vulnerability by sending a request that submits malicious input to the targeted system. A successful exploit could allow the attacker to execute arbitrary commands in a subprocess by using the Ruby Kernel.open method. 

The vendor has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, an attacker must send a request that submits malicious input to the 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

• The vendor has release an issue report at the following link: Issue #1915

Fixed Software

• The vendor has released software updates at the following link: Nokogiri 1.10.4