A vulnerability in the NX-API feature of Cisco NX-OS Software could allow an authenticated, local attacker to execute arbitrary code as root. The vulnerability is due to incorrect input validation in the NX-API feature. An attacker could exploit this vulnerability by sending a crafted HTTP or HTTPS request to an internal service on an affected device that has the NX-API feature enabled. A successful exploit could allow the attacker to cause a buffer overflow and execute arbitrary code as root. Note: The NX-API feature is disabled by default. MDS 9000 Series Multilayer Switches are affected in versions prior to 8.1(1). Nexus 3000 Series Switches are affected in versions prior to 7.0(3)I4(8) and 7.0(3)I7(1). Nexus 3500 Platform Switches are affected in versions prior to 6.0(2)A8(8). Nexus 3600 Platform Switches are affected in versions prior to 7.0(3)F3(5). Nexus 2000, 5500, 5600, and 6000 Series Switches are affected in versions prior to 7.3(2)N1(1). Nexus 7000 and 7700 Series Switches are affected in versions prior to 7.3(3)D1(1). Nexus 9000 Series Switches in Standalone NX-OS Mode are affected in versions prior to 7.0(3)I4(8) and 7.0(3)I7(1). Nexus 9500 R-Series Line Cards and Fabric Modules are affected in versions prior to 7.0(3)F3(5).
The software performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer.
Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data. As a result, an attacker may be able to execute arbitrary code, alter the intended control flow, read sensitive information, or cause the system to crash.
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.
Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows.
For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.
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].