Lenovo stated that two legacy IBM System x server models that were discontinued in 2019 are vulnerable to attack and will not receive security fixes. However, the firm is providing a workaround mitigation solution. 

Both the IBM System x 3550 M3 and IBM System x 3650 M3 are vulnerable to command injection attacks. An attacker can use a vulnerable programme called Integrated Management Module to execute arbitrary instructions on either server model's operating system (IMM). 

IMM performs system management functions. Serial and Ethernet connections on the back panel of System x models use the IMM for device management. 

According to a Lenovo advisory published Tuesday, the flaw is in the IMM firmware code and “could allow the execution of operating system commands over an authenticated SSH or Telnet session.” 

Secure Shell, often known as SSH, is a cryptographic network communication technology that allows two computers to interact or transfer files. Telenet is another network protocol that permits remote users to log into another machine on the same network. Telnet does not encrypt data delivered over its connection by default. 

The flaw, which has been assigned the number CVE-2021-3723, was discovered on Wednesday by Denver Abrey, a bug hunter. 

In June 2020, eight vulnerabilities in a subsequent version of IMM, known as IMM2, were discovered, three of which were of high severity. These issues were found in the client-side code called libssh2, which is accountable for executing the SSH2 protocol. 

The System x 3550 M3 and System x 3650 M3 were announced as medium‐sized corporate solutions on April 5, 2011. Lenovo stated on June 30, 2015, that both systems will be terminated, but security updates would be provided for another five years. 

Software and security support for the System x 3550 and 3650 ended on December 31, 2019, according to the Lenovo security notice. 

Lenovo wrote, “Lenovo has historically provided service and support for at least five years following a product’s withdrawal from marketing. This is subject to change at Lenovo’s sole discretion without notice. Lenovo will announce a product’s EOS date at least 90 days before the actual EOS date and in most cases longer.”

Lenovo stated on Wednesday that it recommends discontinuing the use of both servers, but that it had a mitigation approach. 

If it is not possible to stop using these systems, Lenovo suggests: 

• Disable SSH and Telnet (This can be done in the Security and Network Protocol sections of the navigation pane after logging into the IMM web interface) 
• During initial configuration, change the default Administrator password. 
• Enforce the use of strong passwords. 
• Only give trustworthy admins access. 

Lenovo did not comment if it was familiar with any active campaigns aimed at exploiting the flaw.