1 00:00:00,000 --> 00:00:01,020 In this lesson, 2 00:00:01,020 --> 00:00:02,850 we're going to discuss rootkits. 3 00:00:02,850 --> 00:00:05,160 Now, a rootkit is a specific type of software 4 00:00:05,160 --> 00:00:07,230 that's designed to gain administrative-level control, 5 00:00:07,230 --> 00:00:10,230 over a given computer system without being detected. 6 00:00:10,230 --> 00:00:12,060 Now, this is a really important concept 7 00:00:12,060 --> 00:00:14,490 because if somebody can install a rootkit on your system, 8 00:00:14,490 --> 00:00:15,330 they can gain root 9 00:00:15,330 --> 00:00:17,880 or administrative-level permissions over that system. 10 00:00:17,880 --> 00:00:19,470 And this is the highest level of permissions 11 00:00:19,470 --> 00:00:22,770 that somebody can have on a given computer system or server. 12 00:00:22,770 --> 00:00:25,500 So, if you're using a Windows machine, for example, 13 00:00:25,500 --> 00:00:27,210 the account with the highest level of permission, 14 00:00:27,210 --> 00:00:29,130 is called the administrator account. 15 00:00:29,130 --> 00:00:31,170 That administrator account allows the person 16 00:00:31,170 --> 00:00:33,300 to install programs, delete programs, 17 00:00:33,300 --> 00:00:34,980 open ports, shut ports, 18 00:00:34,980 --> 00:00:36,720 and do pretty much whatever it is they want to do 19 00:00:36,720 --> 00:00:38,490 on that given system. 20 00:00:38,490 --> 00:00:42,090 If the victim is using Unix, Linux or a Mac OS computer, 21 00:00:42,090 --> 00:00:43,410 this type of administrator account, 22 00:00:43,410 --> 00:00:45,420 is actually called the root account. 23 00:00:45,420 --> 00:00:47,190 Either way, getting administrative 24 00:00:47,190 --> 00:00:49,320 or root account access is a wonderful thing 25 00:00:49,320 --> 00:00:51,150 for an attacker or threat actor, 26 00:00:51,150 --> 00:00:53,040 but it is a horrible thing for you 27 00:00:53,040 --> 00:00:55,110 and the security of your system. 28 00:00:55,110 --> 00:00:57,630 So now that you have an understanding of what a rootkit is, 29 00:00:57,630 --> 00:00:59,520 and the type of permissions it's seeking to gain, 30 00:00:59,520 --> 00:01:02,670 let's take a moment to learn how a rootkit actually works. 31 00:01:02,670 --> 00:01:04,230 Now, if you look at a computer system, 32 00:01:04,230 --> 00:01:06,330 it has several different rings of permission used 33 00:01:06,330 --> 00:01:07,500 throughout the system. 34 00:01:07,500 --> 00:01:09,690 The outermost ring is called ring three, 35 00:01:09,690 --> 00:01:12,090 and this is where the user permissions are going to be used. 36 00:01:12,090 --> 00:01:14,880 So if you're logged as a standard or regular user, 37 00:01:14,880 --> 00:01:17,370 you're mostly going to be operating in ring three. 38 00:01:17,370 --> 00:01:19,830 Now, each program can be run in different security rings, 39 00:01:19,830 --> 00:01:22,200 moving from ring three at the outermost level, 40 00:01:22,200 --> 00:01:24,390 all the way down to ring zero at the innermost 41 00:01:24,390 --> 00:01:26,460 or highest permission level in the system. 42 00:01:26,460 --> 00:01:28,020 When you're operating in ring zero, 43 00:01:28,020 --> 00:01:29,970 we call this the kernel mode. 44 00:01:29,970 --> 00:01:32,160 The kernel mode allows the system to control access 45 00:01:32,160 --> 00:01:34,410 to things like the device drivers, your sound card, 46 00:01:34,410 --> 00:01:37,530 your video display or monitor, and other things like that. 47 00:01:37,530 --> 00:01:40,380 Kernel mode or ring zero is not something you're going to log 48 00:01:40,380 --> 00:01:43,110 into the system as, but instead it is the most trusted 49 00:01:43,110 --> 00:01:46,470 and powerful ring inside the operating systems design. 50 00:01:46,470 --> 00:01:48,210 Now, if you log in as the administrator 51 00:01:48,210 --> 00:01:49,740 or route user on a system, 52 00:01:49,740 --> 00:01:51,120 you're going to have route permission, 53 00:01:51,120 --> 00:01:54,210 and you'll be operating at ring one of the operating system. 54 00:01:54,210 --> 00:01:56,670 Now, this is closer to ring zero than ring three was, 55 00:01:56,670 --> 00:01:59,370 so it's easier to do more damage on the system 56 00:01:59,370 --> 00:02:02,070 from ring one than it would be from ring three. 57 00:02:02,070 --> 00:02:03,570 Now, when a root kit is installed, 58 00:02:03,570 --> 00:02:06,240 it tries to gain the highest levels of permission possible. 59 00:02:06,240 --> 00:02:08,280 So any malicious code it's going to execute, 60 00:02:08,280 --> 00:02:10,830 we'll operate in ring one, or if they're lucky, 61 00:02:10,830 --> 00:02:12,780 even as low as ring zero. 62 00:02:12,780 --> 00:02:14,880 Remember, the closer the malicious code is 63 00:02:14,880 --> 00:02:16,440 to ring zero or the kernel, 64 00:02:16,440 --> 00:02:17,910 the more permissions it's going to have 65 00:02:17,910 --> 00:02:20,430 and the more damage it can do on your system. 66 00:02:20,430 --> 00:02:22,200 Now, when a rootkit is installed on a system, 67 00:02:22,200 --> 00:02:24,990 it tries to move itself from ring one to ring zero, 68 00:02:24,990 --> 00:02:26,430 so it can hide from other functions 69 00:02:26,430 --> 00:02:29,190 of your operating system as well to avoid detection. 70 00:02:29,190 --> 00:02:31,920 In fact, rootkits are able to perform malicious operations 71 00:02:31,920 --> 00:02:34,350 on a target computer at any date they want 72 00:02:34,350 --> 00:02:36,990 without the knowledge of the administrators or the users, 73 00:02:36,990 --> 00:02:38,400 and even sometimes without the knowledge 74 00:02:38,400 --> 00:02:41,640 of the operating system itself if they're properly coded. 75 00:02:41,640 --> 00:02:43,860 Remember, a rootkit is designed to really dig 76 00:02:43,860 --> 00:02:45,390 into your operating system deeply. 77 00:02:45,390 --> 00:02:47,550 So your antivirus and anti-malware solutions, 78 00:02:47,550 --> 00:02:50,280 have a really really hard time detecting them. 79 00:02:50,280 --> 00:02:52,290 Now, one technique that's used by rootkits 80 00:02:52,290 --> 00:02:54,300 to gain this deeper level of access is known 81 00:02:54,300 --> 00:02:56,100 as a DLL injection. 82 00:02:56,100 --> 00:02:58,230 Now, a DLL injection is a technique used 83 00:02:58,230 --> 00:03:00,540 to run arbitrary code within the address space 84 00:03:00,540 --> 00:03:02,370 of another process by forcing it 85 00:03:02,370 --> 00:03:04,620 to load a dynamic-link library. 86 00:03:04,620 --> 00:03:07,380 A dynamic-link library, also known as a DLL, 87 00:03:07,380 --> 00:03:09,180 is simply a collection of code and data 88 00:03:09,180 --> 00:03:11,610 that can be used by multiple programs simultaneously 89 00:03:11,610 --> 00:03:13,890 to allow for code reuse and modularization 90 00:03:13,890 --> 00:03:15,210 in software development. 91 00:03:15,210 --> 00:03:17,160 And these DLLs are often provided 92 00:03:17,160 --> 00:03:20,460 by default inside of the Windows operating system. 93 00:03:20,460 --> 00:03:21,960 With a DLL injection, 94 00:03:21,960 --> 00:03:23,370 the malicious code is going to be inserted 95 00:03:23,370 --> 00:03:25,680 into a running process on a Windows machine 96 00:03:25,680 --> 00:03:28,140 by taking advantage of those dynamic-link libraries 97 00:03:28,140 --> 00:03:30,180 that are being loaded up at runtime. 98 00:03:30,180 --> 00:03:31,920 This means that the Windows system, 99 00:03:31,920 --> 00:03:33,270 doesn't even understand the fact 100 00:03:33,270 --> 00:03:36,090 that it has a rootkit installed inside of one of those DLLs 101 00:03:36,090 --> 00:03:36,923 that is then designed 102 00:03:36,923 --> 00:03:39,780 to load every time you boot up a Windows machine. 103 00:03:39,780 --> 00:03:41,970 This kind of DLL injection is going to work 104 00:03:41,970 --> 00:03:43,920 by using what is known as a shim. 105 00:03:43,920 --> 00:03:46,260 Now, a shim is simply a piece of software code 106 00:03:46,260 --> 00:03:47,910 that's placed between two components, 107 00:03:47,910 --> 00:03:50,370 and it intercepts the calls between those two components 108 00:03:50,370 --> 00:03:52,560 and then it can redirect those calls. 109 00:03:52,560 --> 00:03:55,110 So the rootkit will intercept the communications, 110 00:03:55,110 --> 00:03:56,700 between the Windows operating system 111 00:03:56,700 --> 00:03:58,380 and the dynamic-link library, 112 00:03:58,380 --> 00:04:01,230 and then it redirects that call once it's embedded 113 00:04:01,230 --> 00:04:02,610 into some kind of malicious code 114 00:04:02,610 --> 00:04:04,440 that's being embedded inside of it. 115 00:04:04,440 --> 00:04:06,630 Now, these rootkits are extremely powerful, 116 00:04:06,630 --> 00:04:08,430 and they're also very difficult to detect 117 00:04:08,430 --> 00:04:11,280 because the operating system is essentially blinded to them. 118 00:04:11,280 --> 00:04:13,080 To detect them, the best way is to boot 119 00:04:13,080 --> 00:04:14,130 from an external device 120 00:04:14,130 --> 00:04:15,990 and then scan the internal hard disk drive 121 00:04:15,990 --> 00:04:17,250 or solid state device 122 00:04:17,250 --> 00:04:19,110 to ensure you can detect those rootkits, 123 00:04:19,110 --> 00:04:21,300 using a good anti-malware scanning solution 124 00:04:21,300 --> 00:04:23,610 from a live boot Linux distribution. 125 00:04:23,610 --> 00:04:26,580 So remember, a rootkit is a piece of malicious software 126 00:04:26,580 --> 00:04:28,470 that's designed to infiltrate a computer system 127 00:04:28,470 --> 00:04:30,660 at the highest administrative permission level 128 00:04:30,660 --> 00:04:32,610 while remaining undetected. 129 00:04:32,610 --> 00:04:34,110 Rootkits aim to gain access 130 00:04:34,110 --> 00:04:35,880 as close to ring zero as possible, 131 00:04:35,880 --> 00:04:37,290 and they'll start out at ring three, 132 00:04:37,290 --> 00:04:38,700 the user-level permission ring, 133 00:04:38,700 --> 00:04:41,040 and work their way down all the way to ring zero, 134 00:04:41,040 --> 00:04:42,510 the kernel mode permission ring, 135 00:04:42,510 --> 00:04:44,280 where they can wreak the most havoc. 136 00:04:44,280 --> 00:04:45,960 A rootkit's primary objective is 137 00:04:45,960 --> 00:04:48,450 to seamlessly embedded itself into the operating system, 138 00:04:48,450 --> 00:04:49,380 and this is often done 139 00:04:49,380 --> 00:04:51,150 by exploiting the system's inherent trust 140 00:04:51,150 --> 00:04:54,210 in the dynamic link library system or DLL system, 141 00:04:54,210 --> 00:04:57,660 using a DLL injection, and the use of a shim technique. 142 00:04:57,660 --> 00:04:59,850 Because of the deep rooted nature of a rootkit 143 00:04:59,850 --> 00:05:02,310 and its ability to hide itself from the operating system, 144 00:05:02,310 --> 00:05:04,530 traditional antivirus and anti-malware solutions, 145 00:05:04,530 --> 00:05:06,690 will often fail to detect rootkits. 146 00:05:06,690 --> 00:05:08,340 Therefore, the most effective method 147 00:05:08,340 --> 00:05:10,230 for rootkit detection removal is going 148 00:05:10,230 --> 00:05:12,660 to be to conduct an external system scan. 149 00:05:12,660 --> 00:05:14,880 Remember, guarding yourself against rootkits, 150 00:05:14,880 --> 00:05:16,620 does require continuous vigilance 151 00:05:16,620 --> 00:05:19,110 and the implementation of robust security measures, 152 00:05:19,110 --> 00:05:21,183 across your entire enterprise systems.