Use-after-free vulnerability in the NetWare Core Protocol (NCP) feature in Novell eDirectory 8.7.3 SP10 before 8.7.3 SP10 FTF1 and 8.8 SP2 for Windows allows remote attackers to cause a denial of service and possibly execute arbitrary code via a sequence of Get NCP Extension Information By Name requests that cause one thread to operate on memory after it has been freed in another thread, which triggers memory corruption, aka Novell Bug 373852.
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Edirectory | Novell | * | 8.7.3 (excluding) |
| Edirectory | Novell | 8.7.3-sp1 (including) | 8.7.3-sp1 (including) |
| Edirectory | Novell | 8.7.3-sp2 (including) | 8.7.3-sp2 (including) |
| Edirectory | Novell | 8.7.3-sp3 (including) | 8.7.3-sp3 (including) |
| Edirectory | Novell | 8.7.3-sp4 (including) | 8.7.3-sp4 (including) |
| Edirectory | Novell | 8.7.3-sp5 (including) | 8.7.3-sp5 (including) |
| Edirectory | Novell | 8.7.3-sp6 (including) | 8.7.3-sp6 (including) |
| Edirectory | Novell | 8.7.3-sp7 (including) | 8.7.3-sp7 (including) |
| Edirectory | Novell | 8.7.3-sp8 (including) | 8.7.3-sp8 (including) |
| Edirectory | Novell | 8.7.3-sp9 (including) | 8.7.3-sp9 (including) |
| Edirectory | Novell | 8.8 (including) | 8.8 (including) |
The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:
In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.