A flaw was found in the 389-ds-base server. A heap buffer overflow vulnerability exists in the schema_attr_enum_callback function within the schema.c file. This occurs because the code incorrectly calculates the buffer size by summing alias string lengths without accounting for additional formatting characters. When a large number of aliases are processed, this oversight can lead to a heap overflow, potentially allowing a remote attacker to cause a Denial of Service (DoS) or achieve Remote Code Execution (RCE).
Weakness
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | RedHat | 389-ds-base-0:3.1.3-7.el10_1 | * |
| Red Hat Enterprise Linux 9 | RedHat | 389-ds-base-0:2.7.0-10.el9_7 | * |
| Red Hat Directory Server 13.1 | RedHat | dirsrv/dirsrv-container-rhel10:sha256:5e49efa2b8764403fad13b81c968b76c7b6400fabd83bf95e2f7667b90e93ab5 | * |
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].