rework a bit and add gdb info

index.html

@@ -291,12 +291,11 @@ template: inverse
 .right-column[
 In hacking, a shellcode is a small piece of code used as the payload in the exploitation of a software vulnerability. It is called "shellcode" because it typically starts a command shell from which the attacker can control the compromised machine, but any piece of code that performs a similar task can be called shellcode. [1]
 
-Here's a bit of shellcode to open `/bin/sh` on 32-bit x86 (48 bytes) [2]:
+Here's a bit of shellcode to open `/bin/sh` on 32-bit x86 (37 bytes) [2]:
 ```
-\xeb\x11\x5e\x31\xc9\xb1\x32\x80\x6c\x0e\xff\x01\x80\xe9\x01
+\x6a\x17\x58\x31\xdb\xcd\x80\x6a\x2e\x58\x53\xcd\x80\x31\xd2
-\x75\xf6\xeb\x05\xe8\xea\xff\xff\xff\x32\xc1\x51\x69\x30\x30
+\x6a\x0b\x58\x52\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89
-\x74\x69\x69\x30\x63\x6a\x6f\x8a\xe4\x51\x54\x8a\xe2\x9a\xb1
+\xe3\x52\x53\x89\xe1\xcd\x80
-\x0c\xce\x81
 ```
 
 As strings in C are NULL terminated, shellcode should not have `\x00` in it.
@@ -305,7 +304,7 @@ As strings in C are NULL terminated, shellcode should not have `\x00` in it.
 
 Sometimes swapping out some shellcode for some other shellcode is the trick.
 
-.footnote[[1] Borrowed from [wikipedia](https://en.wikipedia.org/wiki/Shellcode)<br>[2] Shellcode from [shell-storm](http://shell-storm.org/shellcode/files/shellcode-491.php)]
+.footnote[[1] Borrowed from [wikipedia](https://en.wikipedia.org/wiki/Shellcode)<br>[2] Shellcode from [shell-storm](http://shell-storm.org/shellcode/files/shellcode-251.php)]
 ]
 ---
 template: inverse
@@ -380,8 +379,7 @@ template: inverse
 .right-column[
 Now it's your turn.
 
-Use google cloudshell https://console.cloud.google.com/cloudshell/ to run ssh to
+Log into the provided VM. Binary and shellcode are in `/smash`
-log into `XX.XX.XX.XX` (not available now) with ssh using user `hulkX` password `smashX`. Binary and shellcode are in `/smash`
 
 **Alternative** If you want to use your own system, Do this as preparation:
 - Install radare2: `$ sudo apt-get install -y radare2`<br>**OR**<br> `$ git clone https://github.com/radareorg/radare2.git && cd radare2 && sys/user.sh`<br>for a persistent installation.
@@ -435,7 +433,7 @@ int main()
 .right-column[
 Now, if you managed that:
 - Try to make it open a shell via shellcode. Especially fun if you make the binary SUID root:<br> `$ sudo chown root.root diy && sudo chmod u+s diy`
-- Can be done both via shellcode in an environment variable (usually more reliable) and via shellcode in the buffer
+- Can be done both via shellcode in an environment variable (usually more reliable **HINT**) and via shellcode in the buffer
 
 Tip: `gets()` behaves weirdly and will close your shell immediately. The trick is to do something like:<br>
 `$ (echo -e MYINPUT; cat)|./diy`<br>
@@ -463,6 +461,24 @@ template: inverse
   - `S` step over
 - `?v HEX` build in calculator (e.g. `?v 0xdead0000+0xbeef`)
 - `?vi HEX` hex to integer (e.g. `?vi 0x400`)
+]
+---
+template: inverse
+# Quick GDB reference
+---
+.left-column[
+## Quick GDB reference
+]
+.right-column[
+- `gdb --args <program> <arguments>` start gdb with a program with arguments
+- `disas <function>` disassemble a function
+- `b *<address>` set a breakpoint on an address
+- `x/200x $esp` show the memory contents for 200 bytes starting at the address $esp points to
+- `r` run
+- `r < foo.txt` run with stdin filled from a file
+- `c` continue
+- `s` step into
+- `info functions` list all functions
 ]
 
     </textarea>