GV-I/O Box 4E is a smart embedded device with 4 input and 4 relays output that can be controlled over Ethernet and RS-485.
DVRSearch is a service running by default on the IOBox listening for UDP messages on port 10001. Any user on the network can send messages to this service and interact with it.
Upon receiving a UDP message, the server reads at most 1460 bytes into a local buffer and a pointer to the buffer is stored in a global variable:
Net Mask field stack overflow
The following code is vulnerable to a stack overflow that is attacker-controlled:
v6 = strlen(g_network_config->net_mask);
memcpy(&reply_buf[184], g_network_config->net_mask, v6);
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].