CVE-2020-11897: Treck TCP/IP Buffer Overflow Vulnerability

CVE-2020-11897 Overview

CVE-2020-11897 is a critical Out-of-Bounds Write vulnerability affecting the Treck TCP/IP stack before version 5.0.1.35. This vulnerability can be exploited remotely via multiple malformed IPv6 packets, potentially allowing attackers to execute arbitrary code, corrupt memory, or cause denial of service conditions on affected devices. This vulnerability is part of the Ripple20 collection of vulnerabilities discovered in the Treck TCP/IP stack, which is widely deployed across embedded systems, IoT devices, and industrial control systems.

Critical Impact

This vulnerability enables remote attackers to trigger an Out-of-Bounds Write condition through malformed IPv6 packets, potentially leading to remote code execution or system compromise without any user interaction or authentication requirements.

Affected Products

• Treck TCP/IP stack versions prior to 5.0.1.35
• Embedded devices and IoT systems utilizing vulnerable Treck TCP/IP implementations
• Industrial control systems and medical devices incorporating the affected networking stack

Discovery Timeline

• June 17, 2020 - CVE-2020-11897 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-11897

Vulnerability Analysis

CVE-2020-11897 is classified as CWE-787 (Out-of-Bounds Write), a memory corruption vulnerability that occurs when the software writes data past the boundaries of allocated memory buffers. In the context of the Treck TCP/IP stack, this flaw manifests during the processing of IPv6 packets. When multiple malformed IPv6 packets are sent to a vulnerable device, the stack fails to properly validate packet boundaries and lengths, resulting in memory writes beyond allocated buffer regions.

The vulnerability is network-accessible, requiring no authentication or user interaction to exploit. An attacker can craft and send malicious IPv6 packets to a vulnerable target, potentially achieving remote code execution or system instability. The scope of this vulnerability extends beyond the vulnerable component itself, as successful exploitation can affect other system resources.

Root Cause

The root cause of this vulnerability lies in improper bounds checking within the Treck TCP/IP stack's IPv6 packet parsing routines. When processing incoming IPv6 packets, the stack fails to adequately validate the length and structure of packet data before writing to memory buffers. This allows carefully crafted malformed packets to trigger write operations outside the intended memory regions, leading to heap or stack corruption depending on the specific exploitation scenario.

Attack Vector

The attack vector for CVE-2020-11897 is network-based, allowing remote exploitation without any privileges or user interaction. An attacker needs network access to send IPv6 packets to a vulnerable device. The attack can be conducted by:

1. Identifying devices running vulnerable versions of the Treck TCP/IP stack
2. Crafting multiple malformed IPv6 packets designed to trigger the Out-of-Bounds Write condition
3. Sending the malicious packets to the target device
4. Achieving memory corruption that may lead to code execution, information disclosure, or denial of service

The vulnerability manifests in the IPv6 packet processing routines of the Treck TCP/IP stack. Malformed packets with improper length fields or fragmentation parameters can trigger writes beyond allocated buffer boundaries. For detailed technical analysis, refer to the JSOF Ripple20 Overview and CERT Advisory ID 257161.

Detection Methods for CVE-2020-11897

Indicators of Compromise

• Unusual IPv6 traffic patterns or malformed IPv6 packets targeting embedded devices
• Unexpected device crashes, reboots, or unstable behavior following network activity
• Anomalous memory consumption or segmentation faults on devices with Treck TCP/IP stack
• Network traffic containing fragmented IPv6 packets with inconsistent length fields

Detection Strategies

• Deploy network intrusion detection systems (IDS) with signatures for Ripple20 exploitation attempts
• Monitor for malformed IPv6 packet sequences targeting embedded devices and IoT infrastructure
• Implement deep packet inspection to identify anomalous IPv6 header values and length inconsistencies
• Utilize endpoint detection and response (EDR) solutions to monitor for memory corruption indicators on supported devices

Monitoring Recommendations

• Enable comprehensive logging of IPv6 traffic at network perimeter and internal segments
• Configure alerts for devices exhibiting unexpected crashes or communication failures
• Establish baseline network behavior for embedded devices to identify deviation patterns
• Monitor vendor security advisories from Cisco, Aruba Networks, and Dell for device-specific guidance

How to Mitigate CVE-2020-11897

Immediate Actions Required

• Identify all devices in your environment using the Treck TCP/IP stack and determine their firmware versions
• Apply vendor-provided patches and firmware updates that address CVE-2020-11897
• Implement network segmentation to isolate vulnerable embedded devices from untrusted networks
• Disable IPv6 on affected devices if not required for operations and if supported by the device
• Deploy firewall rules to restrict IPv6 traffic to and from vulnerable devices

Patch Information

Treck has released version 5.0.1.35 of the TCP/IP stack which addresses this vulnerability. Organizations should contact their device vendors to obtain firmware updates incorporating the patched Treck stack. Many OEMs have released security advisories and patches, including Cisco, Aruba Networks, and Dell. Consult the CERT Advisory ID 257161 for a comprehensive list of affected vendors and their respective patches.

Workarounds

• Disable IPv6 functionality on affected devices where operationally feasible
• Implement strict network access controls limiting IPv6 traffic to trusted sources only
• Deploy network-level filtering to block malformed IPv6 packets before they reach vulnerable devices
• Use VPNs or other secure tunnels to protect traffic to embedded devices from untrusted network paths
• Consider deploying an application-layer gateway or proxy to inspect and sanitize IPv6 traffic

# Example: Disable IPv6 on Linux-based embedded devices (where applicable)
# Add to /etc/sysctl.conf or create /etc/sysctl.d/disable-ipv6.conf
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

# Apply changes without reboot
sysctl -p

# Verify IPv6 is disabled
cat /proc/sys/net/ipv6/conf/all/disable_ipv6