CVE-2023-36831 in Junos OS
Summary
by MITRE • 07/14/2023
An Improper Check or Handling of Exceptional Conditions vulnerability in the UTM (Unified Threat Management) Web-Filtering feature of Juniper Networks Junos OS on SRX Series causes a jbuf memory leak to occur when accessing certain websites, eventually leading to a Denial of Service (DoS) condition. Service restoration is only possible by rebooting the system.
The jbuf memory leak only occurs in SSL Proxy and UTM Web-Filtering configurations. Other products, platforms, and configurations are not affected by this vulnerability.
This issue affects Juniper Networks Junos OS on SRX Series: 22.2 versions prior to 22.2R3; 22.3 versions prior to 22.3R2-S1, 22.3R3; 22.4 versions prior to 22.4R1-S2, 22.4R2.
This issue does not affect Juniper Networks Junos OS versions prior to 22.2R2.
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Analysis
by VulDB Data Team • 08/05/2023
This vulnerability represents a critical improper check or handling of exceptional conditions flaw within the unified threat management web-filtering functionality of juniper networks junos os running on srx series platforms. The issue manifests as a memory leak in the jbuf memory subsystem when processing specific web traffic patterns through ssl proxy and utm web-filtering configurations. This fundamental flaw in exception handling creates a progressive degradation of system resources that ultimately results in complete service denial. The vulnerability specifically targets the interaction between ssl proxy and web-filtering components, where malformed or specially crafted web requests trigger an improper memory management sequence that fails to properly release allocated buffer resources.
The technical exploitation of this vulnerability occurs when legitimate web traffic passes through the affected configurations, causing the jbuf memory allocator to continuously consume system memory without proper deallocation. This memory leak represents a classic resource exhaustion attack vector that operates through the improper handling of exceptional conditions as defined by cwe-703. The flaw demonstrates inadequate error recovery mechanisms within the web-filtering subsystem, where the system fails to gracefully handle certain ssl proxy responses or web content processing scenarios that should be recoverable without system-wide resource consumption. The vulnerability's impact is particularly severe because it affects the core operational functionality of the srx series device, creating a cascading effect that can render the entire security appliance non-functional.
Operational implications of this vulnerability extend beyond simple service disruption to encompass complete system unavailability and potential business impact. The requirement for system reboot to restore service indicates that the memory leak has progressed to a point where the device cannot recover through normal operational procedures or graceful degradation mechanisms. This vulnerability affects multiple junos os versions across the 22.2, 22.3, and 22.4 release streams, creating a broad impact surface that requires immediate attention from network security administrators. The specific version constraints reveal that the issue was introduced in the 22.2 release cycle and persisted through several subsequent minor releases, suggesting a systemic problem in the memory management implementation rather than a transient bug. Network operators must understand that this vulnerability can be exploited remotely through normal web traffic processing, making it particularly dangerous in production environments where continuous availability is critical.
Mitigation strategies for this vulnerability should focus on immediate version upgrades to the patched releases as specified in the advisory. Organizations must prioritize upgrading their srx series devices to versions 22.2R3, 22.3R2-S1, 22.3R3, 22.4R1-S2, or 22.4R2 to eliminate the memory leak condition. Alternative mitigation approaches may include temporary configuration changes that disable specific web-filtering or ssl proxy features during the upgrade process, though this approach reduces security coverage. Network administrators should implement monitoring solutions to detect early signs of memory consumption anomalies that could indicate vulnerability exploitation. The vulnerability's classification under cwe-703 emphasizes the need for comprehensive error handling reviews in security appliance software development processes. From an att&ck framework perspective, this vulnerability aligns with defensive evasion techniques where an attacker could leverage resource exhaustion to maintain persistent access or create conditions for further exploitation. Organizations should also consider implementing network segmentation and traffic filtering to reduce exposure during remediation periods while maintaining overall network security posture.