A Stack-based Buffer Overflow vulnerability in Flow Processing Daemon (flowd) of Juniper Networks Junos OS allows an unauthenticated, network-based attacker to cause Denial of Service (DoS).
On all Junos OS MX Series platforms with SPC3 and MS-MPC/-MIC, when URL filtering is enabled and a specific URL request is received and processed, flowd will crash and restart. Continuous reception of the specific URL request will lead to a sustained Denial of Service (DoS) condition.
This issue affects:
Junos OS:
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all versions before 21.2R3-S6,
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from 21.3 before 21.3R3-S5,
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from 21.4 before 21.4R3-S5,
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from 22.1 before 22.1R3-S3,
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from 22.2 before 22.2R3-S1,
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from 22.3 before 22.3R2-S2, 22.3R3,
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from 22.4 before 22.4R2-S1, 22.4R3.
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).
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].
References