CVE-2021-0230

On Juniper Networks SRX Series devices with link aggregation (lag) configured, executing any operation that fetches Aggregated Ethernet (AE) interface statistics, including but not limited to SNMP GET requests, causes a slow kernel memory leak. If all the available memory is consumed, the traffic will be impacted and a reboot might be required. The following log can be seen if this issue happens. /kernel: rt_pfe_veto: Memory over consumed. Op 1 err 12, rtsm_id 0:-1, msg type 72 /kernel: rt_pfe_veto: free kmem_map memory = (20770816) curproc = kmd An administrator can use the following CLI command to monitor the status of memory consumption (ifstat bucket): user@device > show system virtual-memory no-forwarding | match ifstat Type InUse MemUse HighUse Limit Requests Limit Limit Size(s) ifstat 2588977 162708K - 19633958 «« user@device > show system virtual-memory no-forwarding | match ifstat Type InUse MemUse HighUse Limit Requests Limit Limit Size(s) ifstat 3021629 189749K - 22914415 «« This issue affects Juniper Networks Junos OS on SRX Series: 17.1 versions 17.1R3 and above prior to 17.3R3-S11; 17.4 versions prior to 17.4R3-S5; 18.2 versions prior to 18.2R3-S7, 18.2R3-S8; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R2-S7, 18.4R3-S6; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R1-S6; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R3-S1; 20.1 versions prior to 20.1R2, 20.1R3; 20.2 versions prior to 20.2R2-S2, 20.2R3; 20.3 versions prior to 20.3R1-S2, 20.3R2. This issue does not affect Juniper Networks Junos OS prior to 17.1R3.

Weakness

The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

Affected Software

Extended Description

Limited resources include memory, file system storage, database connection pool entries, and CPU. If an attacker can trigger the allocation of these limited resources, but the number or size of the resources is not controlled, then the attacker could cause a denial of service that consumes all available resources. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system. There are at least three distinct scenarios which can commonly lead to resource exhaustion:

Resource exhaustion problems are often result due to an incorrect implementation of the following situations:

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• https://kb.juniper.net/JSA11125
• https://kb.juniper.net/JSA11125