Executive Summary

This vulnerability is caused by insufficient validation of the prefix length field in IPv6 Router Advertisement processing in FreeRTOS-Plus-TCP versions before V4.2.6 and V4.4.1.

An adjacent network actor can exploit this by sending a specially crafted Router Advertisement with a prefix length value that exceeds the maximum valid length.

This leads to memory corruption through a heap buffer overflow.

Users who only process IPv4 Router Advertisements are not affected by this vulnerability.

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Impact Analysis

The vulnerability can cause memory corruption due to a heap buffer overflow when processing crafted IPv6 Router Advertisements.

This can potentially allow an adjacent network attacker to disrupt the normal operation of the affected device or software.

The impact includes possible denial of service or other unpredictable behavior resulting from the memory corruption.

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Mitigation Strategies

To mitigate this issue, users should upgrade to the fixed version of FreeRTOS-Plus-TCP when it becomes available.

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Compliance Impact

The vulnerability impacts the integrity and availability of affected systems by allowing memory corruption through crafted IPv6 Router Advertisement packets. However, there is no indication that confidentiality is affected.

Since the vulnerability does not impact confidentiality, it is less likely to directly violate data protection regulations such as GDPR or HIPAA, which primarily focus on protecting personal data confidentiality and privacy.

Nevertheless, the potential for system crashes or compromised integrity could indirectly affect compliance if these systems are part of critical infrastructure handling regulated data, as availability and integrity are also important aspects of these standards.

Mitigation by upgrading to fixed versions or implementing network-level filtering is recommended to maintain system security and compliance posture.

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Detection Guidance

This vulnerability involves crafted IPv6 Router Advertisement (RA) packets with invalid prefix length fields causing memory corruption. Detection involves monitoring for unusual or malformed RA packets on the local network.

Network-level filtering or packet inspection tools can be used to detect RA packets with prefix length values exceeding the maximum valid length.

While no specific commands are provided in the resources, typical detection methods include using packet capture tools such as tcpdump or Wireshark to filter and analyze IPv6 RA packets.

• Use tcpdump to capture IPv6 RA packets: tcpdump -i <interface> icmp6 and ip6[40] == 134
• Analyze captured packets in Wireshark to inspect the prefix length field in Router Advertisement messages for values exceeding valid limits.

Additionally, implementing network-level filtering to block untrusted or malformed RA packets can help mitigate exploitation.

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Executive Summary

This vulnerability is an out-of-bounds write issue in the IPv6 Router Advertisement (RA) packet processing of FreeRTOS-Plus-TCP versions before V4.2.6 and V4.4.1. It occurs because the software does not properly validate the prefix length field in RA packets, allowing an attacker on the local network to send a specially crafted RA packet with an invalid prefix length. This causes memory corruption through a heap buffer overflow.

The flaw affects only IPv6 RA processing and does not impact users processing IPv4 RA only.

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Impact Analysis

An attacker on the adjacent network can exploit this vulnerability to cause memory corruption in affected devices. This can lead to a heap buffer overflow, potentially resulting in crashes or compromising the integrity and availability of the device.

The vulnerability does not impact confidentiality but can affect system stability and reliability.

Exploitation requires no authentication or user interaction, making it easier for attackers on the local network to exploit.

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Detection Guidance

This vulnerability involves crafted IPv6 Router Advertisement (RA) packets with invalid prefix length fields causing memory corruption. Detection would involve monitoring network traffic for suspicious or malformed RA packets with prefix length values exceeding the maximum valid length.

While no specific commands are provided in the resources, network administrators can use packet capture tools such as tcpdump or Wireshark to filter and analyze IPv6 RA packets. For example, using tcpdump to capture RA packets:

• tcpdump -i <interface> icmp6 and 'ip6[40] == 134'

This command captures ICMPv6 Router Advertisement messages (ICMPv6 type 134). Further inspection of the prefix length fields in these packets can help identify malformed RA packets that may exploit the vulnerability.

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Mitigation Strategies

The primary mitigation is to upgrade FreeRTOS-Plus-TCP to versions V4.2.6 or V4.4.1, which include patches that properly validate the prefix length field in IPv6 Router Advertisement processing.

If upgrading immediately is not possible, network-level mitigations include filtering or blocking untrusted or rogue IPv6 Router Advertisement packets to prevent exploitation.

Additionally, deploying affected devices on isolated network segments can reduce exposure to malicious RA packets from adjacent network actors.

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