CVE-2020-1678 in Junos
Summary
by MITRE • 10/17/2020
On Juniper Networks Junos OS and Junos OS Evolved platforms with EVPN configured, receipt of specific BGP packets causes a slow memory leak. If the memory is exhausted the rpd process might crash. If the issue occurs, the memory leak could be seen by executing the "show task memory detail | match policy | match evpn" command multiple times to check if memory (Alloc Blocks value) is increasing. root@device> show task memory detail | match policy | match evpn ------------------------ Allocator Memory Report ------------------------ Name | Size | Alloc DTXP Size | Alloc Blocks | Alloc Bytes | MaxAlloc Blocks | MaxAlloc Bytes Policy EVPN Params 20 24 3330678 79936272 3330678 79936272 root@device> show task memory detail | match policy | match evpn ------------------------ Allocator Memory Report ------------------------ Name | Size | Alloc DTXP Size | Alloc Blocks | Alloc Bytes | MaxAlloc Blocks | MaxAlloc Bytes Policy EVPN Params 20 24 36620255 878886120 36620255 878886120 This issue affects: Juniper Networks Junos OS 19.4 versions prior to 19.4R2; 20.1 versions prior to 20.1R1-S4, 20.1R2; Juniper Networks Junos OS Evolved: 19.4 versions; 20.1 versions prior to 20.1R1-S4-EVO, 20.1R2-EVO; 20.2 versions prior to 20.2R1-EVO; This issue does not affect: Juniper Networks Junos OS releases prior to 19.4R1. Juniper Networks Junos OS Evolved releases prior to 19.4R1-EVO.
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Analysis
by VulDB Data Team • 11/20/2020
This vulnerability represents a critical memory management flaw in Juniper Networks Junos OS and Junos OS Evolved platforms that utilize EVPN (Ethernet Virtual Private Network) configurations. The issue manifests through the processing of specific BGP (Border Gateway Protocol) packets that trigger a gradual memory consumption pattern within the rpd (Routing Process Daemon) component. The vulnerability operates as a slow memory leak where allocated memory blocks continuously increase without proper deallocation, ultimately leading to potential process crashes when system memory becomes exhausted. This represents a classic example of a memory leak vulnerability that can be exploited to cause denial of service conditions, as the system gradually consumes available resources until critical operations fail.
The technical implementation of this flaw occurs within the EVPN parameter handling mechanism of the routing process daemon, specifically in how it processes and manages memory allocations for policy EVPN parameters. The memory leak affects the Allocator Memory Report system where the "Alloc Blocks" value shows a steady increase over time, indicating that memory blocks are being allocated but never properly released back to the system. This behavior is particularly concerning because it operates slowly and incrementally, making it difficult to detect during routine monitoring while still eventually causing system instability. The vulnerability affects multiple software versions including various releases of Junos OS 19.4 and 20.1 series, as well as corresponding Evolved platform versions, demonstrating the widespread nature of this memory management issue across different product lines.
The operational impact of this vulnerability extends beyond simple resource consumption to potentially disrupt network services and routing operations. When the rpd process crashes due to memory exhaustion, it can cause routing table inconsistencies, BGP session disruptions, and overall network instability that affects multiple services relying on proper routing functionality. Network administrators may experience intermittent connectivity issues or complete service outages as the system becomes increasingly unstable. The vulnerability's stealthy nature means that operators might not immediately recognize the memory leak pattern, especially in environments with heavy BGP traffic where the leak might be masked by normal operational behavior. This makes the vulnerability particularly dangerous as it can remain undetected for extended periods while gradually degrading system performance.
Mitigation strategies for this vulnerability require immediate implementation of software updates and patches provided by Juniper Networks to address the memory leak in the EVPN processing code. System administrators should also implement monitoring procedures to track memory allocation patterns using the specific commands mentioned in the vulnerability description, such as "show task memory detail | match policy | match evpn" to identify early signs of memory consumption increases. Network segmentation and traffic filtering can help reduce exposure by limiting the types of BGP packets that can reach affected systems, while regular system restart procedures can provide temporary relief by clearing accumulated memory allocations. Organizations should also consider implementing automated alerting systems that can detect unusual memory allocation patterns, aligning with industry best practices for memory leak detection and prevention. This vulnerability demonstrates the importance of proper memory management in network operating systems and highlights the need for continuous security monitoring and patch management processes to protect against such stealthy but impactful flaws.