An issue was discovered in Adobe Acrobat and Reader: 2017.012.20098 and earlier versions, 2017.011.30066 and earlier versions, 2015.006.30355 and earlier versions, and 11.0.22 and earlier versions. This vulnerability is an instance of a use after free vulnerability in the JavaScript engine. The mismatch between an old and a new object can provide an attacker with unintended memory access – potentially leading to code corruption, control-flow hijack, or an information leak attack. Successful exploitation could lead to arbitrary code execution.
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 |
|---|---|---|---|
| Acrobat | Adobe | * | 11.0.22 (including) |
| Acrobat | Adobe | 17.0 (including) | 17.011.30066 (including) |
| Acrobat_dc | Adobe | - (including) | 17.012.20098 (including) |
| Acrobat_dc | Adobe | 15.0 (including) | 15.006.30355 (including) |
| Acrobat_reader | Adobe | * | 11.0.22 (including) |
| Acrobat_reader | Adobe | 17.0 (including) | 17.011.30066 (including) |
| Acrobat_reader_dc | Adobe | - (including) | 17.012.20098 (including) |
| Acrobat_reader_dc | Adobe | 15.0 (including) | 15.006.30355 (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.