The D-Link DCS series of Wi-Fi cameras contains a stack-based buffer overflow in alphapd, the camera’s web server. The overflow allows a remotely authenticated attacker to execute arbitrary code by providing a long string in the WEPEncryption parameter when requesting wireless.htm. Vulnerable devices include DCS-5009L (1.08.11 and below), DCS-5010L (1.14.09 and below), DCS-5020L (1.15.12 and below), DCS-5025L (1.03.07 and below), DCS-5030L (1.04.10 and below), DCS-930L (2.16.01 and below), DCS-931L (1.14.11 and below), DCS-932L (2.17.01 and below), DCS-933L (1.14.11 and below), and DCS-934L (1.05.04 and below).
The software writes data past the end, or before the beginning, of the intended buffer.
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].