Recently it was discovered as a part of the research on IoT devices in the most recent firmware for Shekar Endoscope that an attacker connected to the device Wi-Fi SSID can exploit a memory corruption issue and execute remote code on the device. This device acts as an Endoscope camera that allows its users to use it in various industrial systems and settings, car garages, and also in some cases in the medical clinics to get access to areas that are difficult for a human being to reach. Any breach of this system can allow an attacker to get access to video feed and pictures viewed by that user and might allow them to get a foot hold in air gapped networks especially in case of nation critical infrastructure/industries. The firmware contains binary uvc_stream that is the UDP daemon which is responsible for handling all the UDP requests that the device receives. The client application sends a UDP request to change the Wi-Fi name which contains the following format: SETCMD0001+0001+[2 byte length of wifiname]+[Wifiname]. This request is handled by control_Dev_thread function which at address 0x00409AE0 compares the incoming request and determines if the 10th byte is 01 and if it is then it redirects to 0x0040A74C which calls the function setwifiname. The function setwifiname uses a memcpy function but uses the length of the payload obtained by using strlen function as the third parameter which is the number of bytes to copy and this allows an attacker to overflow the function and control the $PC value.
The product 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.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Endoscope_camera_firmware | Ishekar | * | * |
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.
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.
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]. 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].
Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.
For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].