A Heap-based Buffer Overflow vulnerability in the Routing Protocol Daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network based attacker to cause a Denial of Service (DoS).
If an attacker sends a specific BGP UPDATE message to the device, this will cause a memory overwrite and therefore an RPD crash and restart in the backup Routing Engine (RE). Continued receipt of these packets will cause a sustained Denial of Service (DoS) condition in the backup RE.
The primary RE is not impacted by this issue and there is no impact on traffic.
This issue only affects devices with NSR enabled.
Note: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability. This issue requires an attacker to have an established BGP session to a system affected by the issue. This issue affects both eBGP and iBGP implementations.
This issue affects:
Juniper Networks Junos OS
Juniper Networks Junos OS Evolved
The product writes data past the end, or before the beginning, of the intended buffer.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Junos | Juniper | 20.4 (including) | 20.4 (including) |
| Junos | Juniper | 20.4-r1 (including) | 20.4-r1 (including) |
| Junos | Juniper | 20.4-r1-s1 (including) | 20.4-r1-s1 (including) |
| Junos | Juniper | 20.4-r2 (including) | 20.4-r2 (including) |
| Junos | Juniper | 20.4-r2-s1 (including) | 20.4-r2-s1 (including) |
| Junos | Juniper | 20.4-r2-s2 (including) | 20.4-r2-s2 (including) |
| Junos | Juniper | 20.4-r3 (including) | 20.4-r3 (including) |
| Junos | Juniper | 20.4-r3-s1 (including) | 20.4-r3-s1 (including) |
| Junos | Juniper | 20.4-r3-s2 (including) | 20.4-r3-s2 (including) |
| Junos | Juniper | 20.4-r3-s3 (including) | 20.4-r3-s3 (including) |
| Junos | Juniper | 20.4-r3-s4 (including) | 20.4-r3-s4 (including) |
| Junos | Juniper | 20.4-r3-s5 (including) | 20.4-r3-s5 (including) |
| Junos | Juniper | 20.4-r3-s6 (including) | 20.4-r3-s6 (including) |
| Junos | Juniper | 20.4-r3-s7 (including) | 20.4-r3-s7 (including) |
| Junos | Juniper | 20.4-r3-s8 (including) | 20.4-r3-s8 (including) |
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.
Be wary that a language’s interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
Consider adhering to the following rules when allocating and managing an application’s memory:
Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.
For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].