In LoRa Basics Station before 2.0.4, there is a Use After Free vulnerability that leads to memory corruption. This bug is triggered on 32-bit machines when the CUPS server responds with a message (https://doc.sm.tc/station/cupsproto.html#http-post-response) where the signature length is larger than 2 GByte (never happens in practice), or the response is crafted specifically to trigger this issue (i.e. the length signature field indicates a value larger than (2**31)-1 although the signature actually does not contain that much data). In such a scenario, on 32 bit machines, Basic Station would execute a code path, where a piece of memory is accessed after it has been freed, causing the process to crash and restarted again. The CUPS transaction is typically mutually authenticated over TLS. Therefore, in order to trigger this vulnerability, the attacker would have to gain access to the CUPS server first. If the user chose to operate without authentication over TLS but yet is concerned about this vulnerability, one possible workaround is to enable TLS authentication. This has been fixed in 2.0.4.
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 |
|---|---|---|---|
| Lora_basics_station | Semtech | * | 2.0.4 (excluding) |
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.