So, you've dropped the laptop and the fan became noisy, which would also lead to CPU throttling because if the fan isn't working right, CPU is going to overheat and your laptop is going to suffer as the result of this.
Did you even take the back off to try to reseat it or clean up the laptop? You can try to take it to an authorized Apple repair shop to see if they can re-seat the fan/clean up the fans for you.
I have same '12 rMBP and the performance is just as snappy as it was back in '12 and I've never reinstall OS either, so it's all consistent and snappy.
I have no plans to upgrade this because there's nothing else that comes close to replacing it right now, not even '16 rMBP.
As for the disk, I put my VMs on external SSDs, works great. Certainly cheaper than replacing the laptop and easier to upgrade every year to more storage.
As a normal user, grepping these values I actually get 0000000000000000. I can't imagine these being the actual values. Is it possible that because I remount my /proc with the hidepid=2 option the values are not visible for normal non-root accounts?
No, it would seem (I'm not sure though) that this happens for you because your distro is smart enough to have a nice security setting be on by default. The setting / sysctl can be changed at:
/proc/sys/kernel/kptr_restrict
For me, this gave me 0, but if you cat this it should give you 1. So essentially it's a setting but I'd wager it's not related to you remounting /proc.
Just for curiosity's sake, from searching around it seems that this particular security feature (hide kernel pointers for unprivileged users) seems to have originated from this commit (which in itself implements a broader and more general security feature): http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.g... - but it's often not enabled.
So it's not ASLR or anything to do with filesystem options (per se), but rather a custom "kptr_restrict" kernel vs. userspace security feature provided by the kernel:
"[...] The %pK format specifier is designed to hide exposed kernel pointers,
specifically via /proc interfaces. Exposing these pointers provides an
easy target for kernel write vulnerabilities, since they reveal the
locations of writable structures containing easily triggerable function
pointers." (Dan Rosenberg, 2011-01-13 - nice.) (Of course if there's no ASLR and one knows which distro is being targeted, it's possible to find those values on another machine and to just bake them into the exploit, as others have pointed out. Also, other channels exist for finding these addresses, etc.)
That only hides the pid directories of others users, and indeed on my system remounting /proc with hidepid=2 I'm still able to see the same values for kallsyms. Maybe your kernel is compiled without the CONFIG_KEYS=y option? (I'm spitballing here).
No, the bug is in the kernel keyring facility, so if I'm not mistaken compiling with CONFIG_KEYS=n option should protect you (I haven't tested though). As for the /proc/kallsyms, I honestly don't know how come you only get zeroes.
EDIT: The obvious question I should have asked is which distro you are running. Also, as others have pointed out, hoping that the attacker can't read kallsyms from the machine he's attacking is not really a good defense plan.
I'm running Ubuntu 14.04 which should be affected. I just hoped it would be harder without having the correct kallsyms version. It seems I will have no options except to reboot my cluster :)
make sure you have privileges to read that file. I ran grep without sudo and got that address on Ubuntu 15.10, but with sudo it will display an actual address.
The file /proc/kallsyms contains the addresses of various kernel functions: it's useful when you've already exploited a vulnerability in the kernel, and you want to do something useful with it, e.g. escalate your userspace process to root. In theory, since you're running code in kernelspace, you can do whatever; in practice it's much easier to start with known functions that can manipulate the data structures for you.
Think of it like the manual of a nuclear missile launcher. Obviously they don't want to give that out to everyone. But if you can break into the room with the launcher's control panel, you've still caused a major security breach even if you have no idea what to do next. Having the manual just makes your job easier, but the attack was that you broke in in the first place; they can't count on you being unable to figure out how to work the panel.
Also, if you're running a binary kernel (for instance, a kernel built by your Linux distro), the addresses in kallsyms are going to be constant for everyone running that distro. Hiding kallsyms for non-root users is primarily useful for people who build custom kernels.
Production-level malware often also has code that doesn't depend on having access to kallsyms and is more advanced (e.g., starting from the system call interrupt vector and disassembling it and seeing what addresses are jumped to). Using kallsyms is good for keeping a simple proof-of-concept exploit readable.
The /proc/kallsyms values are identical across identical kernel compilations.
Suppose you have a vulnerable CentOS 7 system that you want to exploit - you could get the proper addresses from your own CentOS 7 VM running the same kernel, apply those to a modified exploit compilation, and run that compilation on your target host.
Also, it is not bullet proof because apparently there are lots of info leaks in linux and I think linux also does not reboot after a panic (http://www.cyberciti.biz/tips/reboot-linux-box-after-a-kerne...) so if the entropy for KASLR is small enough you can retry very aggressively. Though in this particular instance if you have to wait 30 minutes between each try that would kill brute forcing.
Not sure if the poster is also the author but why is the application connecting to a server? Is it using a centralised point to connect to the Bitmessage network?
Edit: It also appears to connect to Tor. Perhaps a quick overview of what's happening under the hood could be useful.
Me and a friend created Snapshare. The design part took up way to much time for us since we are both hardcore coders, we will be bringing a dedicated designer on the team next year. It was loads of fun though and we created a good codebase to build upon.
