CVE-2020-35683 in NicheStack
Summary
by MITRE • 08/19/2021
An issue was discovered in HCC Nichestack 3.0. The code that parses ICMP packets relies on an unchecked value of the IP payload size (extracted from the IP header) to compute the ICMP checksum. When the IP payload size is set to be smaller than the size of the IP header, the ICMP checksum computation function may read out of bounds, causing a Denial-of-Service.
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Analysis
by VulDB Data Team • 08/21/2021
The vulnerability identified as CVE-2020-35683 resides within the HCC Nichestack 3.0 network stack implementation, representing a critical flaw in how ICMP packet processing handles payload size validation. This issue demonstrates a classic example of improper input validation that can lead to memory corruption and system instability. The affected software component processes Internet Control Message Protocol packets through a parsing routine that fails to properly validate the relationship between IP header fields and payload dimensions, creating a scenario where maliciously crafted packets can trigger unexpected behavior in the network stack.
The technical root cause of this vulnerability stems from the ICMP checksum computation function's reliance on an unchecked IP payload size value extracted directly from the IP header without proper bounds verification. When an attacker crafts an ICMP packet with an IP payload size field set to a value smaller than the actual IP header size, the parsing code attempts to compute the checksum using invalid memory offsets. This condition creates a buffer over-read scenario where the checksum calculation routine accesses memory locations beyond the intended payload boundaries. The vulnerability specifically manifests when the payload size parameter becomes negative or smaller than expected, causing the software to perform memory operations that exceed allocated buffer limits.
From an operational impact perspective, this vulnerability presents a significant denial-of-service risk that can compromise the availability of network services running on systems utilizing HCC Nichestack 3.0. The out-of-bounds memory access can result in application crashes, system instability, or complete service unavailability, potentially affecting network infrastructure, servers, or embedded devices that depend on this networking stack. The vulnerability is particularly concerning because it can be triggered through simple ICMP packet injection without requiring authentication or elevated privileges, making it accessible to any network entity capable of sending ICMP traffic to the target system.
The flaw aligns with CWE-129, which addresses improper validation of array indices, and CWE-787, concerning out-of-bounds write operations, though the specific manifestation here involves read operations rather than writes. This vulnerability also maps to ATT&CK technique T1499.001, which covers network denial of service attacks, and T1071.004, covering application layer protocol traffic. The attack surface is broad as any system running HCC Nichestack 3.0 and processing ICMP traffic is potentially vulnerable, including enterprise servers, network appliances, and embedded systems that may be exposed to untrusted network traffic. The vulnerability's impact is amplified in environments where ICMP traffic is not filtered or where systems are configured to process all incoming ICMP packets without proper validation mechanisms.
Mitigation strategies should focus on implementing proper input validation for IP header fields, particularly the payload size parameter, before any checksum computation occurs. The recommended approach involves adding boundary checks to ensure that the payload size value is consistent with the IP header size and that the calculated memory access offsets remain within valid buffer boundaries. Additionally, implementing proper error handling for malformed packets and adding defensive programming practices such as bounds checking, memory access validation, and input sanitization can prevent exploitation of this vulnerability. System administrators should also consider network segmentation and ICMP filtering where appropriate, though the most effective long-term solution requires patching the affected software components to include proper validation logic that prevents the out-of-bounds memory access condition from occurring during ICMP packet processing.