By overlong input values an attacker may force overwrite of the internal program stack in SAP Web Dispatcher - versions 7.53, 7.77, 7.81, 7.85, 7.86, or Internet Communication Manager - versions KRNL64NUC 7.22, 7.22EXT, 7.49, KRNL64UC 7.22, 7.22EXT, 7.49, 7.53, KERNEL 7.22, 7.49, 7.53, 7.77, 7.81, 7.85, 7.86, which makes these programs unavailable, leading to denial of service.
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).
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Netweaver | Sap | 7.22ext (including) | 7.22ext (including) |
| Netweaver | Sap | 7.49 (including) | 7.49 (including) |
| Netweaver | Sap | 7.53 (including) | 7.53 (including) |
| Netweaver | Sap | 7.77 (including) | 7.77 (including) |
| Netweaver | Sap | 7.81 (including) | 7.81 (including) |
| Netweaver | Sap | 7.85 (including) | 7.85 (including) |
| Netweaver | Sap | 7.86 (including) | 7.86 (including) |
| Netweaver | Sap | kernel_7.22 (including) | kernel_7.22 (including) |
| Netweaver | Sap | krnl64nuc_7.22 (including) | krnl64nuc_7.22 (including) |
| Netweaver | Sap | krnl64uc_7.22 (including) | krnl64uc_7.22 (including) |
| Web_dispatcher | Sap | 7.53 (including) | 7.53 (including) |
| Web_dispatcher | Sap | 7.77 (including) | 7.77 (including) |
| Web_dispatcher | Sap | 7.81 (including) | 7.81 (including) |
| Web_dispatcher | Sap | 7.85 (including) | 7.85 (including) |
| Web_dispatcher | Sap | 7.86 (including) | 7.86 (including) |
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].