Rating:
# rev70 - 'ServerfARM'
> Someone handed me this and told me that to pass the exam, I have to
> extract a secret string. I know cheating is bad, but once does not count.
> So are you willing to help me?
> Attachment: [rev70.zip](./rev70.zip)
Once we open up [rev70.zip](./rev70.zip) we'll see there's a file called **serverfarm** with no extension.
Pop that into IDA and we get that it's an ARM ELF file. Well in my current position, whether it be too lazy or incapable, I won't be able to run this ARM ELF file on this machine. So let's look around.
There's a little segment that allows for input (**scanf**) to be passed into a function called **handle_task**
Let's check out that function.
It's a switch-case woo!~
Now unfortunately I'm not rich so I don't have the newest version to use it's ARM64 Decompiler. Luckily there's an[ awesome website that can do decompilation with all the important/well-known processors for FREE :D](https://retdec.com/decompilation/) (I like free o3o)
Running that through gives us some awesome pictures and psuedocode.
This one being the most interesting, the layout of handle_task:
Well I was right when I said it was a switch-case statement. So first we do the first 'block' notified by the string saying so: **Here's your 1. block**
We have:
```c
printf("%s", "IW{"); // Start of flag: "IW{"
putchar(83); // putchar writes a character to stdout: 83 = 'S'
printf("%c%c\n", 46, 69); // printf of two characters: 46, 69 = '.E'
```
Onto the next task and block by case 1:
via execution flow
```c
printf("%s", ".R."); // write ".R."
putchar(86); // write 'V'
printf("%c%c\n", 46, 69); // write ".E"
```
The next task/block by case 2:
```c
puts(".R>=F:"); // Write ".R>=F:"
```
And the final one lol:
```c
printf("%c%s%c\n", 65, ":R:M", 125); // Write "A:R:M}"
```
And there's our flag
```
IW{S.E.R.V.E.R>=F:A:R:M}
```
:3
