CVE-2020-11900 Overview
CVE-2020-11900 is a Double Free vulnerability affecting the Treck TCP/IP stack before version 6.0.1.41. This vulnerability exists within the IPv4 tunneling implementation and is part of the broader "Ripple20" collection of vulnerabilities discovered in the widely deployed Treck TCP/IP stack. The Treck TCP/IP stack is embedded in millions of IoT devices, industrial control systems, medical equipment, and enterprise networking products across numerous vendors, making this vulnerability particularly impactful.
Critical Impact
A network-based attacker can exploit the double free condition in IPv4 tunneling to potentially corrupt memory, cause denial of service, or achieve limited integrity impact on affected embedded systems without requiring authentication or user interaction.
Affected Products
- Treck TCP/IP stack versions prior to 6.0.1.41
- Embedded devices and IoT systems utilizing vulnerable Treck TCP/IP implementations
- Products from multiple vendors including Cisco, HPE, Intel, Dell, Aruba Networks, and NetApp
Discovery Timeline
- 2020-06-17 - CVE-2020-11900 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2020-11900
Vulnerability Analysis
The vulnerability is classified as CWE-415 (Double Free), a memory corruption class where a program incorrectly frees the same memory allocation twice. In the context of the Treck TCP/IP stack, this flaw resides in the IPv4 tunneling functionality, which handles encapsulated IP packets within IP datagrams.
When processing IPv4 tunneled traffic, the stack improperly manages memory allocation and deallocation sequences. The double free condition occurs when memory associated with tunneled packet processing is freed once during normal operations, and then freed again due to flawed error handling or state management logic. This leads to heap corruption that can be triggered remotely over the network without any authentication requirements or user interaction.
Root Cause
The root cause stems from improper memory management within the IPv4 tunneling code path of the Treck TCP/IP stack. The implementation fails to properly track the state of allocated memory buffers during tunnel packet processing, resulting in scenarios where the same memory region is deallocated multiple times. This type of vulnerability typically arises from missing or incorrect pointer nullification after freeing memory, or from inadequate synchronization in multi-threaded processing contexts.
Attack Vector
The attack vector is network-based, allowing remote exploitation without authentication. An attacker can craft malicious IPv4 tunneled packets and send them to a vulnerable device. The processing of these specially crafted packets triggers the double free condition, potentially leading to:
- Denial of Service: Heap corruption causing system crashes or hangs
- Limited Integrity Impact: Potential for controlled memory manipulation depending on heap state
- Exploitation Chain Component: Could be combined with other Ripple20 vulnerabilities for more severe attacks
The vulnerability affects the network stack at a low level, meaning exploitation can occur against any device using the vulnerable Treck TCP/IP implementation that processes IPv4 tunneled traffic.
Detection Methods for CVE-2020-11900
Indicators of Compromise
- Unexpected system crashes or reboots in embedded devices and IoT systems
- Anomalous IPv4 tunneling traffic (IP-in-IP, GRE) targeting vulnerable devices
- Memory corruption errors or heap-related faults in device logs
- Network traffic patterns consistent with Ripple20 exploitation attempts
Detection Strategies
- Implement network intrusion detection signatures for malformed IPv4 tunneled packets targeting the Treck stack
- Deploy deep packet inspection to identify exploitation attempts against embedded devices
- Monitor for unusual encapsulated IP traffic patterns on networks containing IoT devices
- Utilize SentinelOne Singularity to detect exploitation behavior and memory corruption indicators on supported endpoints
Monitoring Recommendations
- Enable verbose logging on network boundary devices and firewalls monitoring IPv4 tunnel traffic
- Establish baseline traffic patterns for IoT and embedded devices to detect anomalies
- Monitor vendor security advisories from Cisco, HPE, Intel, and other affected vendors for device-specific guidance
- Conduct regular network asset discovery to identify devices running vulnerable Treck TCP/IP implementations
How to Mitigate CVE-2020-11900
Immediate Actions Required
- Inventory all devices that may contain the Treck TCP/IP stack and prioritize patching
- Apply vendor-specific firmware updates that address the Ripple20 vulnerabilities
- Implement network segmentation to isolate vulnerable IoT and embedded devices from untrusted networks
- Disable IPv4 tunneling functionality where not required on vulnerable devices
- Block or filter IPv4-in-IPv4 and other encapsulated traffic at network perimeters where possible
Patch Information
Treck has released version 6.0.1.41 and later which addresses this vulnerability. However, due to the nature of embedded systems, patching requires obtaining updated firmware from the device manufacturer rather than directly from Treck. Consult the following vendor resources for device-specific patches:
- CERT Vulnerability Note VU#257161 for comprehensive affected product list
- Cisco Security Advisory
- Aruba Networks Security Alert
- Dell Response to Ripple20
- NetApp Security Advisory
For more information on the Ripple20 vulnerability collection, see the JSOF Ripple20 Overview.
Workarounds
- Implement strict network access controls limiting which systems can communicate with vulnerable devices
- Deploy network-level filtering to block malformed or suspicious IPv4 tunneled traffic
- Use VPN or other encrypted tunneling to protect vulnerable devices from direct network exposure
- Place vulnerable embedded systems behind firewalls that can perform deep packet inspection
- Consider decommissioning or replacing devices where vendor patches are unavailable
# Example: Block IP-in-IP protocol (protocol 4) at firewall perimeter
# This helps reduce attack surface for IPv4 tunneling exploits
iptables -A INPUT -p 4 -j DROP
iptables -A FORWARD -p 4 -j DROP
# For GRE tunnel traffic (protocol 47) if not needed
iptables -A INPUT -p 47 -j DROP
iptables -A FORWARD -p 47 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
