An Uncontrolled Resource Consumption vulnerability in the
Layer 2 Address Learning Daemon (l2ald)
of Juniper Networks Junos OS Evolved allows an unauthenticated, adjacent attacker to cause a memory leak, eventually exhausting all system memory, leading to a system crash and Denial of Service (DoS).
Certain MAC table updates cause a small amount of memory to leak. Once memory utilization reaches its limit, the issue will result in a system crash and restart.
To identify the issue, execute the CLI command:
user@device> show platform application-info allocations app l2ald-agent EVL Object Allocation Statistics:
Node Application Context Name Live Allocs Fails Guids re0 l2ald-agent net::juniper::rtnh::L2Rtinfo 1069096 1069302 0 1069302 re0 l2ald-agent net::juniper::rtnh::NHOpaqueTlv 114 195 0 195
This issue affects Junos OS Evolved:
All versions before 21.4R3-S8-EVO,
from 22.2-EVO before 22.2R3-S4-EVO,
from 22.3-EVO before 22.3R3-S3-EVO,
from 22.4-EVO before 22.4R3-EVO,
from 23.2-EVO before 23.2R2-EVO.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Junos_os_evolved | Juniper | * | 21.4 (excluding) |
| Junos_os_evolved | Juniper | 21.4 (including) | 21.4 (including) |
| Junos_os_evolved | Juniper | 21.4-r1 (including) | 21.4-r1 (including) |
| Junos_os_evolved | Juniper | 21.4-r1-s1 (including) | 21.4-r1-s1 (including) |
| Junos_os_evolved | Juniper | 21.4-r1-s2 (including) | 21.4-r1-s2 (including) |
| Junos_os_evolved | Juniper | 21.4-r2 (including) | 21.4-r2 (including) |
| Junos_os_evolved | Juniper | 21.4-r2-s1 (including) | 21.4-r2-s1 (including) |
| Junos_os_evolved | Juniper | 21.4-r2-s2 (including) | 21.4-r2-s2 (including) |
| Junos_os_evolved | Juniper | 21.4-r3 (including) | 21.4-r3 (including) |
| Junos_os_evolved | Juniper | 21.4-r3-s1 (including) | 21.4-r3-s1 (including) |
| Junos_os_evolved | Juniper | 21.4-r3-s2 (including) | 21.4-r3-s2 (including) |
| Junos_os_evolved | Juniper | 21.4-r3-s3 (including) | 21.4-r3-s3 (including) |
| Junos_os_evolved | Juniper | 21.4-r3-s4 (including) | 21.4-r3-s4 (including) |
| Junos_os_evolved | Juniper | 21.4-r3-s5 (including) | 21.4-r3-s5 (including) |
| Junos_os_evolved | Juniper | 21.4-r3-s6 (including) | 21.4-r3-s6 (including) |
| Junos_os_evolved | Juniper | 21.4-r3-s7 (including) | 21.4-r3-s7 (including) |
| Junos_os_evolved | Juniper | 22.2 (including) | 22.2 (including) |
| Junos_os_evolved | Juniper | 22.2-r1 (including) | 22.2-r1 (including) |
| Junos_os_evolved | Juniper | 22.2-r1-s1 (including) | 22.2-r1-s1 (including) |
| Junos_os_evolved | Juniper | 22.2-r1-s2 (including) | 22.2-r1-s2 (including) |
| Junos_os_evolved | Juniper | 22.2-r2 (including) | 22.2-r2 (including) |
| Junos_os_evolved | Juniper | 22.2-r2-s1 (including) | 22.2-r2-s1 (including) |
| Junos_os_evolved | Juniper | 22.2-r2-s2 (including) | 22.2-r2-s2 (including) |
| Junos_os_evolved | Juniper | 22.2-r3 (including) | 22.2-r3 (including) |
| Junos_os_evolved | Juniper | 22.2-r3-s1 (including) | 22.2-r3-s1 (including) |
| Junos_os_evolved | Juniper | 22.2-r3-s2 (including) | 22.2-r3-s2 (including) |
| Junos_os_evolved | Juniper | 22.2-r3-s3 (including) | 22.2-r3-s3 (including) |
| Junos_os_evolved | Juniper | 22.3 (including) | 22.3 (including) |
| Junos_os_evolved | Juniper | 22.3-r1 (including) | 22.3-r1 (including) |
| Junos_os_evolved | Juniper | 22.3-r1-s1 (including) | 22.3-r1-s1 (including) |
| Junos_os_evolved | Juniper | 22.3-r1-s2 (including) | 22.3-r1-s2 (including) |
| Junos_os_evolved | Juniper | 22.3-r2 (including) | 22.3-r2 (including) |
| Junos_os_evolved | Juniper | 22.3-r2-s1 (including) | 22.3-r2-s1 (including) |
| Junos_os_evolved | Juniper | 22.3-r2-s2 (including) | 22.3-r2-s2 (including) |
| Junos_os_evolved | Juniper | 22.3-r3 (including) | 22.3-r3 (including) |
| Junos_os_evolved | Juniper | 22.3-r3-s1 (including) | 22.3-r3-s1 (including) |
| Junos_os_evolved | Juniper | 22.3-r3-s2 (including) | 22.3-r3-s2 (including) |
| Junos_os_evolved | Juniper | 22.4 (including) | 22.4 (including) |
| Junos_os_evolved | Juniper | 22.4-r1 (including) | 22.4-r1 (including) |
| Junos_os_evolved | Juniper | 22.4-r1-s1 (including) | 22.4-r1-s1 (including) |
| Junos_os_evolved | Juniper | 22.4-r1-s2 (including) | 22.4-r1-s2 (including) |
| Junos_os_evolved | Juniper | 22.4-r2 (including) | 22.4-r2 (including) |
| Junos_os_evolved | Juniper | 22.4-r2-s1 (including) | 22.4-r2-s1 (including) |
| Junos_os_evolved | Juniper | 22.4-r2-s2 (including) | 22.4-r2-s2 (including) |
| Junos_os_evolved | Juniper | 23.2 (including) | 23.2 (including) |
| Junos_os_evolved | Juniper | 23.2-r1 (including) | 23.2-r1 (including) |
| Junos_os_evolved | Juniper | 23.2-r1-s1 (including) | 23.2-r1-s1 (including) |
| Junos_os_evolved | Juniper | 23.2-r1-s2 (including) | 23.2-r1-s2 (including) |
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.