1
00:00:01,590 --> 00:00:11,450
We can use the Linux command, see harsh mod or change more to change permissions of the file or folder.

2
00:00:13,170 --> 00:00:19,680
Uh, this is the common thing that people use in this next year when a root user or the files owner

3
00:00:19,680 --> 00:00:21,460
can change permissions.

4
00:00:21,900 --> 00:00:28,630
In this lecture, we use a C judgment to change permission on hash.

5
00:00:28,680 --> 00:00:37,110
Get that he's seen that start using two different methods versus using numerical representation of permissions.

6
00:00:37,110 --> 00:00:39,360
And then we use a symbolic representation.

7
00:00:40,910 --> 00:00:48,500
Changing permissions with decimal notation, we can use a shortcut to refer now to permission by using

8
00:00:48,500 --> 00:00:56,030
a symbol, a single number to represent one, our double helix set of permissions.

9
00:00:56,480 --> 00:01:01,730
So like everything underlying the operating system, the permissions are represented in binary.

10
00:01:02,090 --> 00:01:07,250
So on and off switches are represented by one and zero, respectively.

11
00:01:08,150 --> 00:01:14,060
You can think of the RW X permissions on a string on off switches.

12
00:01:14,060 --> 00:01:23,480
So when all the emissions are granted, this equates in a one on one in binary and binary sit like this

13
00:01:23,480 --> 00:01:32,000
is them, then easily represented as one digit by converting it into a octal and each digit number system

14
00:01:32,000 --> 00:01:35,400
that starts with zero and ensuites seven.

15
00:01:36,230 --> 00:01:46,160
So and this represents a set of three binary digits, meaning we can represent an entire W P R W, except

16
00:01:46,160 --> 00:01:48,290
with one just the one digit.

17
00:01:48,520 --> 00:01:55,780
Uh, this can be zero one two three four five six seven eight seven, actually.

18
00:01:55,810 --> 00:01:57,200
Lastly, 7.8.

19
00:01:57,860 --> 00:01:58,970
So um.

20
00:02:02,670 --> 00:02:09,000
Here I will create a table here for a better understanding here.

21
00:02:09,420 --> 00:02:14,640
So in binary and here this is the binary here.

22
00:02:15,490 --> 00:02:17,910
Uh, octal, octal.

23
00:02:17,940 --> 00:02:23,030
And I will show you here is our W X.

24
00:02:24,720 --> 00:02:25,820
Our top picks.

25
00:02:26,320 --> 00:02:36,480
So the binary is zero, if binary zero zero zero octal is zero smell and RW, it's not read on or write

26
00:02:36,480 --> 00:02:37,710
nor execute yet.

27
00:02:38,640 --> 00:02:43,980
So if binary zero zero one here okodili, there's going to be one.

28
00:02:44,160 --> 00:02:46,550
And this can be not really.

29
00:02:46,560 --> 00:02:49,890
It's not right, but execute executable here.

30
00:02:50,400 --> 00:03:01,050
If binary is zero one zero and octal is two, then this means this is them not readable but readable

31
00:03:01,050 --> 00:03:03,330
and not executable here.

32
00:03:04,380 --> 00:03:10,830
And if binary zero one one and octal is three, then this means.

33
00:03:12,940 --> 00:03:22,000
This is not readable, but rewritable here and executable, if binary is one zero zero.

34
00:03:22,620 --> 00:03:24,880
And this man in octal for.

35
00:03:26,440 --> 00:03:27,010
So.

36
00:03:28,230 --> 00:03:34,650
This means this is not treated, is sexual readable, not rewritable, nor executable.

37
00:03:35,700 --> 00:03:44,340
And if there is one zero one, this means in Oakdale is five here and this is readable.

38
00:03:45,010 --> 00:03:47,010
Um, this is readable.

39
00:03:47,250 --> 00:03:48,180
Not right.

40
00:03:48,180 --> 00:03:50,520
Bill and executable here.

41
00:03:50,520 --> 00:03:52,260
And so readable.

42
00:03:52,440 --> 00:03:54,450
Not readable and executable.

43
00:03:55,620 --> 00:03:59,130
And here we have six and seven.

44
00:03:59,130 --> 00:04:09,000
Lastly, one one zero equals just six in October by a system here, and this is the readable writable

45
00:04:09,450 --> 00:04:10,770
executable here.

46
00:04:11,220 --> 00:04:20,360
But if the binary is one three one one one one, and this means in Oakdale, we have seven here.

47
00:04:21,070 --> 00:04:24,130
Um, and this is readable, right?

48
00:04:24,150 --> 00:04:26,490
Well and executable as well.

49
00:04:27,360 --> 00:04:31,380
So using this information, let's go through some examples.

50
00:04:31,980 --> 00:04:39,030
First, if you want to set only the read permission, we called off the table and look at the value

51
00:04:39,450 --> 00:04:39,990
for it.

52
00:04:39,990 --> 00:04:42,120
For example, this is the read permission.

53
00:04:42,820 --> 00:04:44,190
And this is the fourth.

54
00:04:44,580 --> 00:04:53,280
We can declare this using four or just read, write, execute, or we can declare it in binary.

55
00:04:53,640 --> 00:05:00,450
Next, if we want to set permission to write and execute, we could use the same methodology and look

56
00:05:00,450 --> 00:05:08,300
for what's said and what sets the W and what system is which is executable and write about.

57
00:05:09,180 --> 00:05:15,120
So as you can see here, no, we have our W X here.

58
00:05:15,570 --> 00:05:18,430
So we want just write about the exhibit unexcusable.

59
00:05:18,480 --> 00:05:21,000
And as you can see in Oakdale, this is them.

60
00:05:21,690 --> 00:05:22,080
Three.

61
00:05:22,740 --> 00:05:24,720
So the binary zero one one.

62
00:05:26,020 --> 00:05:26,440
So.

63
00:05:29,930 --> 00:05:35,540
Now we can, um, pass an argument here is a very short comment.

64
00:05:36,050 --> 00:05:36,620
Come in.

65
00:05:36,890 --> 00:05:43,700
So for example, let's, uh, create a new file or fear here of the Cuban section.

66
00:05:43,850 --> 00:05:44,210
OK.

67
00:05:44,860 --> 00:05:45,890
Uh, for example.

68
00:05:47,650 --> 00:05:51,810
Torch here, uh, it's um.

69
00:05:52,060 --> 00:05:53,160
Oh, what's?

70
00:05:54,590 --> 00:05:55,940
Polls while.

71
00:05:57,710 --> 00:06:00,710
Unless there, as you can see here, we create except for.

72
00:06:01,170 --> 00:06:02,830
While this is not enough.

73
00:06:03,350 --> 00:06:05,850
This has not incited any thing.

74
00:06:05,870 --> 00:06:08,690
There's just a file with zero lights here.

75
00:06:09,050 --> 00:06:21,140
So let's declare Ellis L.A. As you can see here, we have example file here, which is created by county.

76
00:06:21,740 --> 00:06:30,510
So let's cheng this permission to, uh uh, let's see how much seven seven four hash, actually.

77
00:06:31,260 --> 00:06:32,960
Example file.

78
00:06:34,820 --> 00:06:40,940
Unless L.A. and as you can see here, we changed these permissions it.

79
00:06:42,690 --> 00:06:43,080
So.

80
00:06:47,820 --> 00:06:58,640
Uh, you shall see R W here, R W X R W E S R e r on the left side of the this example file.

81
00:06:59,060 --> 00:07:04,430
So this confirms that that is, uh, see how someone can successfully change permission on the file

82
00:07:04,610 --> 00:07:10,160
to give the both the owner and the group ability to execute the file.

83
00:07:28,690 --> 00:07:36,610
So Europe's use of permission to protect users or groups files and directories from other users in the

84
00:07:36,610 --> 00:07:40,870
system can be used for offensive and defensive purposes.

85
00:07:41,380 --> 00:07:42,600
Little no, no.

86
00:07:43,120 --> 00:07:48,760
Now know how to manage these permissions and how to exploit weak points in the security system.

87
00:07:49,150 --> 00:07:51,680
In particular, Estudiantes guided.