Friday, November 06, 2015

Is Linux kernel secure?

I've read a article "Net of insecurityThe kernel of the argument" from The Washington Post today. It's fuc*ing good one. I've been torturing by the security status of *stable* linux kernel for a fuc*ing long time. I never see one article can talk about the truth like this one. Many commercial customers( especially from financial data centres) has been painful to use commercial GNU/Linux products for years. Remember those 0ld good null-deref exploits and Enlightment framework back in 2000s? What did Linus and these commercial GNU/Linux vendors response back then? They said "A bug is bug" is one thing, while SELinux can protect your asset is another. Unfortunately, they are lies to you, as always.......

I'm not going to talk about those shitty history right here. You can google if you really want to know the truth. A little advice, you could start from here.

Well, speaking of the history of mitigation. I'm highly recommend you should go through thinkist's presentation at BH'10. Who the hell can explain the history so detailed like he did;-)

Black Hat USA 2010: Memory Corruption Attacks: The Almost Complete History


"As long as there is technology, there will be hackers. As long as there are hackers, there will be PHRACK magazine."( Quoted from Phrack Issue 63). As long as there are vulnerabilities, there will be exploits. As long as there are exploits, there will be mitigation.........

Basically, the possible evolution of a exploitable bug should be look like this:
Bug –> exploitable bug(vulnerability) –> poc –> exploit –> reliable/weaponized exploit

That's where the problem comes. There are two types of philosophical ideas about how to deal with exploitable bug.

1, Linus Torvalds represent the philosophy of "A bug is bug", which believes any exploitable bug should be taken care of like the normal bug. When one is being found, just get to fix it. Any security mitigation is fully waste of CPU usage. Developers should've only focus on the features and performance. He( and his followers) even believes bug info's obscurity is the way to prevent attacker and "security through obscurity" is an effective approach for Linux kernel upstream.

2, PaX Team and spender are the most fascinating guys on the side of security mitigation. They( I) believes numerous exploitable bugs can not be solved once for all by fixing them. But we can design some specific security mitigation to against the specific types of vulnerabilities. That's the only way to solve this issue.

Well, those two philosophical ideas are totally different. Why the hell happens? IMOHO, one of main reasons is the threat model is totally different. In my own adversary, the attackers may have the weaponized exploits, which developed by digital armory( Vupen, HT?) or underground. While only the skiddies in Linus's threat model( it seems to be at least;-)).

Some commercial GNU/Linux vendors basically believes public exploit is the most important reason to influence their risk assessment. Don't believe that? They admitted by themselves;-)

A lot of my customers always says one of reasons they choose GNU/Linux as their alternatives of UNIX, because GNU/Linux is secure. I've been wondering all the time and response like "ARE U fuc*ing serious?". Now GNU/Linux is dive into the next age of Internet, which some people would like to call IoT( internet of the things). But the question is: Is Linux kernel ready to face the tons of cybercriminals? You fuc*ing tell me........

btw: Kernel/Compiler/Firmware are very important core infrastructures of modern cyber world. A lot of good people are busy to defend our world by their effort. PaX/Grsecurity guys are my heros. Reproducible builds( based on the theory of DDC, by David A. Wheeler) is definitely gonna piss NSA off. CHIPSEC( for firmware) may be the starting point. I do believe only the fined FOSS solution can make this world a little more secure......


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