zlacker

>>Harvey+(OP)
The linked blog assures people that this can't be used to access data. Once something is crashing an app/OS, can you really say that? I mean, can you be sure there's no one clever enough to capitalize on the underlying software error leading to this state?

>>menaci+q9
That would be a general issue with app crashing, and a huge deal worth it’s own series of articles. iOS’ sandboxing makes it so unlikely this exists, it’s not worth mentioning and the sensational writing might be counterproductive to getting the actual issue fixed. To use an analogy, it’d be like mentioning that someone could hack Google in an article about Gmail downtime.

>>112358+2f
I see your point, but I actually think users should be _more_ alarmed when an input makes software crash, for just this reason. They tend to think of it as a harmless annoyance.

Also, while sandboxing may be designed to prevent this, Messages is probably also designed not to crash on link sharing.

>>menaci+Uf
There's far more risk in software not crashing when it gets malformed or otherwise unexpected input. If an application crashes, it's memory space has been relinquished and its execution process aborted. Yes, something could've been spawned, but... in general crashing when something unexpected comes up is more sensible, desirable behaviour.

(Or am I wrong? I'm not a professional programmer. I'm just reasoning from common sense.)

>>qubex+dC
The bug causing this crash might be exploitable. Think of a classic buffer overflow: if you overflow a buffer with all zeroes or random data, then the return address most likely gets overwritten with garbage that doesn't point to valid code or a mapped address and the process crashes. But if the attacker specially chose the data they put in the buffer, then they could choose to overwrite the return address with a valid memory address and make the process execute the attacker's own code.

If software written in C/C++ crashes and it's not because of a null pointer dereference specifically, then it's realistic to worry about whether it might be because of an exploitable bug (like a buffer overflow, a double-free, etc). One common way for people to try to find exploitable bugs is to script a program to re-run with random input data to figure out which inputs crash it, and then they debug the crashes to see if they're caused by exploitable bugs.

>>AgentM+wG
The text-segment of the code containing the machine instructions is in read-only memory. You won't be able to overflow a heap variable with the intention of writing to the text-segment of memory without causing a segfault.

>>blackf+YN
But with ROP, there's usually no need to write into the text-segment to execute arbitrary code.

>>0x0+V11
In order to do ROP, you need to chain together gadgets of code segments which means you need to be able to see the source code/binary. This doesn't reveal any information about the call stack nor the available libraries to chain together ROP. And that's if stack canaries haven't screwed things up already.