CISA Issues ICS Advisory for New Vulnerabilities in Treck TCP/IP Stack

Security updates available for the Treck TCP/IP stack address two critical vulnerabilities leading to remote code execution or denial-of-service. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued an advisory to warn organizations using industrial control systems (ICS) about the risks posed by these flaws.

A low-level TCP/IP software library, the Treck TCP/IP stack is specifically designed for embedded systems, featuring small critical sections and a small code footprint. CISA says the product is used worldwide in the critical manufacturing, IT, healthcare and transportation sectors.

Last week, a series of four new vulnerabilities that Intel’s security researchers discovered in the Treck TCP/IP stack were made public. Two of these were rated critical severity.

The most severe of the two is CVE-2020-25066 (CVSS score of 9.8), a heap-based buffer overflow bug in the Treck HTTP Server components that could be abused by attackers to cause denial of service or execute code remotely.

Next in line is CVE-2020-27337 (CVSS score of 9.1), an out-of-bounds write in the IPv6 component that could be exploited by an unauthenticated user to cause a DoS condition via network access.

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An out-of-bounds read in the DHCPv6 client component of Treck IPv6 could be abused by an unauthenticated user to cause denial-of-service via adjacent network access. The bug is tracked as CVE-2020-27338 (CVSS score of 5.9).

The fourth issue, CVE-2020-27336 (CVSS score 3.7), is an improper input validation in the IPv6 component that could lead to an out-of-bounds read of up to three bytes via network access, also without authentication.

Users are advised to install the latest version of the affected product (Treck TCP/IP or later), which can be obtained via email from security(at)

“Treck recommends users who cannot apply the latest patches to implement firewall rules to filter out packets that contain a negative content length in the HTTP header,” CISA’s advisory reads.

To minimize the risk of exploitation, users should ensure that control systems are not accessible from the Internet, they should isolate control system networks and remote devices from the business network and behind a firewall, and should use secure methods, such as VPNs, for remote access.

Just as these new vulnerabilities were publicly disclosed, security firm Forescout announced the release of an open-source script that can help identify the use of TCP/IP stacks vulnerable to the recently disclosed AMNESIA33 set of vulnerabilities.

“Although the script has been tested with the four stacks affected by AMNESIA:33 in a lab environment, we cannot guarantee its use to be safe against every possible device. […] Therefore, we do not recommend using it directly in live environments with mission-critical devices,” Forescout notes.

Related: ‘AMNESIA:33’ Vulnerabilities in TCP/IP Stacks Expose Millions of Devices to Attacks

Related: Ripple20: Flaws in Treck TCP/IP Stack Expose Millions of IoT Devices to Attacks

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Ionut Arghire is an international correspondent for SecurityWeek.

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