A certain sequence of valid BGP or IPv6 BFD packets may trigger a stack based buffer overflow in the Junos OS Packet Forwarding Engine manager (FXPC) process on QFX5000 series, EX4300, EX4600 devices. This issue can result in a crash of the fxpc daemon or may potentially lead to remote code execution. Affected releases are Juniper Networks Junos OS on QFX 5000 series, EX4300, EX4600 are: 14.1X53; 15.1X53 versions prior to 15.1X53-D235; 17.1 versions prior to 17.1R3; 17.2 versions prior to 17.2R3; 17.3 versions prior to 17.3R3-S2, 17.3R4; 17.4 versions prior to 17.4R2-S1, 17.4R3; 18.1 versions prior to 18.1R3-S1, 18.1R4; 18.2 versions prior to 18.2R2; 18.2X75 versions prior to 18.2X75-D30; 18.3 versions prior to 18.3R2.
Weakness
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Junos | Juniper | 15.1x53 (including) | 15.1x53-d235 (excluding) |
| Junos | Juniper | 17.1 (including) | 17.1r3 (excluding) |
| Junos | Juniper | 17.2 (including) | 17.2r3 (excluding) |
| Junos | Juniper | 17.3 (including) | 17.3r3-s2 (excluding) |
| Junos | Juniper | 17.4 (including) | 17.4r2-s1 (excluding) |
| Junos | Juniper | 18.1 (including) | 18.1r3-s1 (excluding) |
| Junos | Juniper | 18.2 (including) | 18.2r2 (excluding) |
| Junos | Juniper | 18.2x75 (including) | 18.2x75-d30 (excluding) |
| Junos | Juniper | 18.3 (including) | 18.3r2 (excluding) |
| Junos | Juniper | 14.1x53 (including) | 14.1x53 (including) |
| Junos | Juniper | 17.3 (including) | 17.3 (including) |
| Junos | Juniper | 17.4 (including) | 17.4 (including) |
| Junos | Juniper | 18.1 (including) | 18.1 (including) |
Potential Mitigations
- 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.
- 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].