In Bareos Director less than or equal to 16.2.10, 17.2.9, 18.2.8, and 19.2.7, a heap overflow allows a malicious client to corrupt the directors memory via oversized digest strings sent during initialization of a verify job. Disabling verify jobs mitigates the problem. This issue is also patched in Bareos versions 19.2.8, 18.2.9 and 17.2.10.
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 |
| Bareos |
Bareos |
* |
16.2.10 (including) |
| Bareos |
Bareos |
17.2.4 (including) |
17.2.9 (including) |
| Bareos |
Bareos |
18.2.5 (including) |
18.2.8 (including) |
| Bareos |
Bareos |
18.4.1 (including) |
19.2.7 (including) |
| Bareos |
Bareos |
18.2.4-rc1 (including) |
18.2.4-rc1 (including) |
| Bareos |
Bareos |
18.2.4-rc2 (including) |
18.2.4-rc2 (including) |
| Bacula |
Ubuntu |
bionic |
* |
| Bacula |
Ubuntu |
trusty |
* |
| Bacula |
Ubuntu |
xenial |
* |
| Bareos |
Ubuntu |
trusty |
* |
| Bareos |
Ubuntu |
xenial |
* |
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