CVE-2021-28362 in Contiki
Summary
by MITRE • 03/24/2021
An issue was discovered in Contiki through 3.0. When sending an ICMPv6 error message because of invalid extension header options in an incoming IPv6 packet, there is an attempt to remove the RPL extension headers. Because the packet length and the extension header length are unchecked (with respect to the available data) at this stage, and these variables are susceptible to integer underflow, it is possible to construct an invalid extension header that will cause memory corruption issues and lead to a Denial-of-Service condition. This is related to rpl-ext-header.c.
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Analysis
by VulDB Data Team • 04/04/2021
The vulnerability identified as CVE-2021-28362 represents a critical memory corruption flaw within the Contiki operating system version 3.0 and earlier. This issue manifests specifically when the system processes incoming IPv6 packets containing invalid extension header options, triggering an ICMPv6 error response mechanism. The underlying problem stems from inadequate validation of packet length and extension header length parameters during the RPL (Routing Protocol for Low-Power and Lossy Networks) extension header removal process. The vulnerability is particularly concerning as it operates at the network protocol level where malformed packets can be crafted to exploit the system's handling of these edge cases.
The technical exploitation of this vulnerability relies on integer underflow conditions that occur when the system attempts to process extension headers without proper bounds checking against available packet data. When an attacker crafts a malicious IPv6 packet with malformed extension header options, the system's rpl-ext-header.c module fails to validate that the calculated header lengths do not exceed the actual packet boundaries. This unchecked arithmetic operation creates a scenario where the system attempts to access memory locations beyond the legitimate packet data, resulting in memory corruption that can manifest as unpredictable behavior or complete system crashes. The vulnerability's classification aligns with CWE-129, which addresses insufficient validation of length fields, and CWE-191, which covers integer underflow conditions.
The operational impact of this vulnerability extends beyond simple denial-of-service conditions to potentially enable more sophisticated attacks within constrained network environments. In IoT and embedded systems where Contiki is commonly deployed, such as sensor networks and low-power devices, this vulnerability could allow remote attackers to disrupt network operations without requiring local access or elevated privileges. The memory corruption issues can lead to system instability, packet loss, or complete device failure, which is particularly problematic in mission-critical applications where network reliability is paramount. Attackers could exploit this vulnerability to create persistent disruption in sensor networks, industrial control systems, or other environments where Contiki-based devices operate.
Mitigation strategies for CVE-2021-28362 should focus on implementing comprehensive bounds checking mechanisms within the packet processing pipeline, particularly in the RPL extension header handling code. System administrators should prioritize updating to Contiki versions that address this vulnerability through proper integer overflow/underflow validation and memory boundary checks. Network administrators can implement additional monitoring to detect malformed ICMPv6 error messages or unusual packet patterns that may indicate exploitation attempts. The fix should incorporate defensive programming practices such as validating all length parameters against available data before performing arithmetic operations, implementing proper error handling for edge cases, and ensuring that extension header processing routines include robust input validation. Organizations should also consider network segmentation and access controls to limit the potential impact of successful exploitation attempts, particularly in environments where Contiki-based systems serve critical infrastructure functions. This vulnerability demonstrates the importance of rigorous input validation in network protocol implementations and aligns with ATT&CK technique T1499.001, which covers network disruption through resource exhaustion or corruption.