CVE-2019-9183 in Contiki
Summary
by MITRE
An issue was discovered in Contiki-NG through 4.2 and Contiki through 3.0. A buffer overflow is present due to an integer underflow during 6LoWPAN fragment processing in the face of truncated fragments in os/net/ipv6/sicslowpan.c. This results in accesses of unmapped memory, crashing the application. An attacker can cause a denial-of-service via a crafted 6LoWPAN frame.
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Analysis
by VulDB Data Team • 06/02/2024
The vulnerability CVE-2019-9183 represents a critical buffer overflow condition affecting Contiki-NG versions through 4.2 and Contiki versions through 3.0, specifically within the 6LoWPAN fragment processing mechanism. This issue manifests in the os/net/ipv6/sicslowpan.c file where the implementation fails to properly validate fragment length parameters during packet reassembly operations. The flaw occurs when the system encounters truncated 6LoWPAN fragments, creating a scenario where integer underflow conditions lead to improper memory access patterns that ultimately result in application crashes.
The technical root cause of this vulnerability stems from an integer underflow condition that occurs during the processing of 6LoWPAN fragments within the IPv6 over Low-Power Wireless Area Networks implementation. When the system receives a malformed or truncated 6LoWPAN frame, the fragment processing logic fails to correctly handle the boundary conditions, causing integer variables to wrap around to negative values. This underflow condition directly impacts the memory allocation calculations used for fragment reassembly, leading to attempts to access memory locations that are either unmapped or outside the intended buffer boundaries. The vulnerability is categorized under CWE-129 as an "Improper Validation of Array Index" and specifically relates to improper handling of integer underflows in memory management operations.
The operational impact of CVE-2019-9183 extends beyond simple application crashes to represent a significant denial-of-service threat in IoT and embedded networking environments. The vulnerability affects wireless sensor networks and other low-power IoT deployments that rely on Contiki's 6LoWPAN implementation for IPv6 communication over low-rate networks. An attacker capable of transmitting maliciously crafted 6LoWPAN frames can trigger the buffer overflow condition, causing the affected device to crash and restart, effectively denying legitimate network services to authorized users. This makes the vulnerability particularly dangerous in mission-critical IoT deployments where continuous network availability is essential. The attack surface is broad as any device implementing Contiki or Contiki-NG with 6LoWPAN support could be affected, including smart meters, environmental sensors, and industrial monitoring systems.
Mitigation strategies for CVE-2019-9183 should focus on both immediate patching and defensive programming practices. The primary solution involves upgrading to Contiki-NG version 4.3 or later, where the integer underflow condition has been corrected through proper input validation and boundary checking mechanisms. Organizations should also implement network monitoring to detect anomalous 6LoWPAN traffic patterns that might indicate exploitation attempts. Defensive measures include implementing rate limiting on fragment processing, adding additional input validation checks for fragment length parameters, and deploying intrusion detection systems that can identify malformed 6LoWPAN frames. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 for Network Denial of Service and T1595.001 for Network Device Firmware, as it exploits weaknesses in embedded networking stack implementations. The vulnerability also aligns with T1071.004 for Application Layer Protocol and T1566.002 for Pre-Attack Phase, as it represents a foundational weakness that can be leveraged for broader network compromise in IoT environments.