It is not "some people" that I worry about. I worry about attackers with a level of skill.
As I noted elsewhere in the thread, I have audited obfuscated code and the obfuscation is only a speed bump. I can only presume that attackers are smarter than I am, and obfuscation is effectively not an issue. And it is not an order of magnitude. This is another example of developer thinking that this form of obscurity is of any real value. Reviewing code will tell you if eigenvector_coefficient is really what it claims to be or something that morphed into something that the developer didn't originally intend.
Also keep in mind that code reviews approach code from a totally different angle than a developer would either developing or during a code walkthrough.
Developers often have some idealized notion that an attacker is going to need to piece their program logic back together and try to decode the purpose of each obfuscated variable in order to find a hardcoded password/value.
In reality an attacker is just going to dump strings and try them all or simply set a breakpoint just before the important syscall and let your program do the work. Code obfuscation provides little to no value for these common methods, yet we cannot resist the urge to list it as a bullet point in security meetings, leading to a false sense of security.
I knew nothing about this topic in general, but elsewhere in this thread there was a link to a blog post about obfuscation methods used in a piece of commercial software. One item was a function that detects a breakpoint, obfuscates its boolean return value so you can't tell if it did, and makes the program hang when it does. Pretty neat.
I think your (and my) ignorance of such methods is evidence that they probably are reasonably effective, even though when explained, they're not quantum physics.
Even OP's advice about running services on non-standard ports isn't sound. Who doesn't run a service scan? Even sites like Shodan do service discovery for you. I'm going to find whatever port your running ssh on if your running it.
I still think it's a good idea. With SSH on port 22, ten thousand bots plus an attacker try to hammer it (so says fail2ban). With SSH on port 9278, zero bots plus an attacker try to hammer it. By throwing away the 99.99% of the chaff, you can see the remaining wheat you care about.
Changing SSH ports isn't about saying "yep, we fixed it!" and calling it a day. It's about decreasing the amount of stuff you have to deal with, which is quite useful. It's something you can do in addition to everything else that gives a decent bang for its buck. No, it doesn't keep you out, but it does keep out those thousands of bots crawling around looking for an open 22 to pester.
> So let’s talk about security by obscurity. It’s a bad idea to use it as a single layer of defense. If the attacker passes it, there is nothing else to protect you. But it’s actually would be good to use it as an “additional” layer of defense. Because it has a low implementation cost and it usually works well.
I think it's good to do those things in addition to the other stuff. Obscurity isn't sufficient by itself, but is another layer of defense.
Not if you have to port knock before the ssh port is open to new connections.
For all you know you have to knock ports 22, 46, 1776, and 8998 to the timing of "shave and a haircut" switching between udp and icmp along the way... Good luck, the entropy you have to overcome is astronomical.
There is still some information lost in the process:
- "let eigenvector_coefficient = 23" => "let x = 23"
A de-obfuscator isn't going to be able to recover the valuable information contained in the original name. Will it stop a determined attacker? Maybe not, but it would surely slow them down as they now need to spend an order of magnitude longer trying to understand what the code is doing.
> Randomizing variable names it just a nuisance, it won't stop any competent pen tester or attacker.
Believe it or not, nuisances are enough to stop some people. A lot of would be attackers are just cruising for low hanging fruit.
Remember, the goal is to "reduce risk" and not "stop any highly skilled targeted/tailored attack". Because let's face it, even if you are the greatest crypto wizard in the world, you will fall victim to a highly sophisticated attack tailored specifically to you.