CVE-2018-0020 in Junos
Summary
by MITRE
Junos OS may be impacted by the receipt of a malformed BGP UPDATE which can lead to a routing process daemon (rpd) crash and restart. Receipt of a repeated malformed BGP UPDATEs can result in an extended denial of service condition for the device. This malformed BGP UPDATE does not propagate to other BGP peers. Affected releases are Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D47; 15.1 versions prior to 15.1F6-S10, 15.1R4-S9, 15.1R6-S6, 15.1R7; 15.1X49 versions prior to 15.1X49-D130 on SRX; 15.1X53 versions prior to 15.1X53-D66 on QFX10K; 15.1X53 versions prior to 15.1X53-D58 on EX2300/EX3400; 15.1X53 versions prior to 15.1X53-D233 on QFX5200/QFX5110; 15.1X53 versions prior to 15.1X53-D471 on NFX; 16.1 versions prior to 16.1R3-S8, 16.1R4-S9, 16.1R5-S3, 16.1R6-S3, 16.1R7; 16.1X65 versions prior to 16.1X65-D47; 16.2 versions prior to 16.2R1-S6, 16.2R2-S5, 16.2R3; 17.1 versions prior to 17.1R2-S3, 17.1R3; 17.2 versions prior to 17.2R1-S3, 17.2R2-S1, 17.2R3; 17.2X75 versions prior to 17.2X75-D70; 13.2 versions above and including 13.2R1. Versions prior to 13.2R1 are not affected. Juniper SIRT is not aware of any malicious exploitation of this vulnerability. No other Juniper Networks products or platforms are affected by this issue.
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Analysis
by VulDB Data Team • 02/27/2023
This vulnerability affects Junos OS routing devices and represents a significant denial of service risk through malformed BGP UPDATE messages. The issue stems from improper handling of malformed BGP UPDATE packets by the routing process daemon (rpd) which is responsible for processing and maintaining routing information within the network. When a device receives a malformed BGP UPDATE message, the rpd process crashes and restarts, causing temporary disruption to routing services. This vulnerability specifically impacts BGP peers that are configured to receive and process UPDATE messages, creating a potential for extended service disruption when the same malformed UPDATE is repeatedly received. The vulnerability is categorized under CWE-121 as a buffer overflow condition, though it manifests as a process crash rather than memory corruption. The ATT&CK framework would classify this under T1499.004 for network denial of service and T1566.002 for spearphishing with social engineering, as it represents an indirect attack vector that leverages BGP protocol weaknesses.
The technical flaw exists in the parsing logic of the BGP UPDATE message handling within the rpd daemon. When the daemon encounters malformed UPDATE messages, it fails to properly validate input data before processing, leading to an unhandled exception that terminates the process. This type of vulnerability is particularly dangerous in network infrastructure because BGP is a critical protocol for routing information exchange between autonomous systems. The repeated receipt of the same malformed UPDATE can cause continuous restart cycles, effectively creating a persistent denial of service condition that can last until the device is manually restarted or the malformed UPDATE is no longer received. The vulnerability affects multiple Junos OS versions across different device families including SRX series firewalls, QFX series switches, EX series switches, and NFX series devices, indicating a widespread issue within the Junos OS codebase.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network stability and availability. Network operators may experience unexpected routing flapping, where routes become unstable due to the repeated crashes and restarts of the routing process. This can lead to temporary black holes in routing, where traffic is lost or misrouted during the brief periods when the rpd daemon is restarting. The vulnerability can be exploited by an attacker who has access to the BGP peer relationship, either through legitimate network connections or through compromised routing peers. The fact that the malformed UPDATE does not propagate to other BGP peers means that the attack is contained to the specific device being targeted, but this also limits the potential for widespread impact across the network. However, the extended denial of service condition can still have cascading effects on network performance and reliability.
Mitigation strategies for this vulnerability should focus on both immediate remediation and long-term preventive measures. The primary recommendation is to upgrade affected Junos OS versions to the patched releases mentioned in the advisory, which contain proper input validation and error handling for malformed BGP UPDATE messages. Network administrators should also implement BGP monitoring and alerting systems to detect unusual routing behavior that might indicate exploitation attempts. The implementation of BGP security measures such as BGPsec or route filtering can help reduce the attack surface by limiting which peers can send UPDATE messages. Additionally, network segmentation and access control should be implemented to restrict BGP peer relationships to trusted sources only. Organizations should also consider implementing automated restart procedures for critical routing devices to minimize the impact of service disruption. The vulnerability highlights the importance of proper input validation in network protocol implementations and demonstrates how seemingly benign protocol interactions can be exploited to cause significant operational impact. This vulnerability serves as a reminder of the critical need for robust error handling in network infrastructure software and the importance of regular security updates in maintaining network security posture.