An issue was discovered in OpenSatKit 2.2.1. The DirName field in the telecommand is provided by the ground segment and must be treated as untrusted input. The program copies DirName into the local buffer DirWithSep using strcpy. The size of this buffer is OS_MAX_PATH_LEN. If the length of DirName is greater than or equal to OS_MAX_PATH_LEN, a stack buffer overflow occurs, overwriting adjacent stack memory. The path length check (FileUtil_AppendPathSep) is performed after the strcpy operation, meaning the validation occurs too late and cannot prevent the overflow.
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
- https://gist.github.com/jonafk555
- https://github.com/OpenSatKit/OpenSatKit
- https://github.com/OpenSatKit/OpenSatKit/releases/tag/v2.2.1
- https://raw.githubusercontent.com/OpenSatKit/OpenSatKit/master/cfs/apps/filemgr/fsw/src/dir.c
- https://raw.githubusercontent.com/OpenSatKit/OpenSatKit/master/cfs/apps/filemgr/fsw/src/dir.c#:~:text=strcpy%28DirWithSep