CVE-2013-5209 in Communications Session Border Controller
Summary
by MITRE
The sctp_send_initiate_ack function in sys/netinet/sctp_output.c in the SCTP implementation in the kernel in FreeBSD 8.3 through 9.2-PRERELEASE does not properly initialize the state-cookie data structure, which allows remote attackers to obtain sensitive information from kernel stack memory by reading packet data in INIT-ACK chunks.
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Analysis
by VulDB Data Team • 12/19/2020
The vulnerability identified as CVE-2013-5209 represents a critical information disclosure flaw within the Stream Control Transmission Protocol implementation in FreeBSD kernel versions 8.3 through 9.2-PRERELEASE. This issue resides in the sctp_send_initiate_ack function located in the sys/netinet/sctp_output.c file, where improper initialization of the state-cookie data structure creates a pathway for remote attackers to access sensitive kernel memory contents. The vulnerability specifically manifests during the processing of INIT-ACK chunks, which are fundamental components of the SCTP handshake process used to establish connections between network endpoints.
The technical nature of this flaw stems from insufficient memory initialization practices within the kernel's SCTP implementation. When the sctp_send_initiate_ack function processes incoming INIT chunks and generates corresponding INIT-ACK responses, it fails to properly initialize certain fields within the state-cookie structure before populating them with data. This incomplete initialization leaves uninitialized memory contents, potentially containing sensitive kernel data, within the state-cookie structure that gets transmitted in the INIT-ACK packet. Remote attackers can exploit this by sending carefully crafted INIT chunks to target systems, receiving the malformed INIT-ACK responses, and extracting kernel stack memory contents that were never properly cleared or overwritten.
The operational impact of CVE-2013-5209 extends beyond simple information disclosure, as the leaked kernel memory may contain critical system information including cryptographic keys, session tokens, buffer contents, and other sensitive data that could be leveraged for further attacks. This vulnerability directly violates the principle of least privilege and information hiding that are fundamental to secure system design. The attack vector requires only network connectivity to the affected system and does not require authentication or specific privileges, making it particularly dangerous as it can be exploited by any remote attacker. According to CWE classification, this vulnerability maps to CWE-248, which addresses "Uncaught Exception" and improper handling of uninitialized memory, while the ATT&CK framework would categorize this under T1005 for Data from Local System and potentially T1566 for Phishing with Malicious Attachments if attackers leverage the leaked information for more sophisticated attacks.
Mitigation strategies for CVE-2013-5209 focus primarily on immediate system updates and patches provided by FreeBSD. Organizations should prioritize upgrading to FreeBSD versions 9.2-STABLE or later where this vulnerability has been addressed through proper initialization of the state-cookie data structure. Additionally, network segmentation and firewall rules can be implemented to restrict access to SCTP services, reducing the attack surface. Monitoring network traffic for unusual INIT-ACK packet patterns and implementing intrusion detection systems can help identify exploitation attempts. System administrators should also consider disabling SCTP if it is not actively required, as this eliminates the attack surface entirely. The fix implemented by FreeBSD developers specifically addresses the uninitialized memory issue by ensuring proper initialization of the state-cookie structure before data is written to it, preventing the leakage of kernel stack contents through network packets.