bowling

الأربعاء، 20 مايو 2020

HTML5 Games On Android

On my last hollidays, I made two HTML5 games, and published on android market. Nowadays javascript has powerful libraries for doing almost everything, and also there are several compilers from java or c code to javascript, converting opengl c code to html5 canvas, but definitely, javascript execution is slower than dalvik applications, and of course much slower than arm c libs. For improving the speed of sounds and images loader, I have used javascript asynchronous execution and scheduling priority has been controlled with setTimeout/setInterval which deprioritize or priorize a code block. This games are published on the android market here: Android Planets and here: Far Planet Related links

الثلاثاء، 19 مايو 2020

Linux Command Line Hackery Series - Part 6

Welcome back to Linux Command Line Hackery series, I hope you've enjoyed this series so far and would have learned something (at least a bit). Today we're going to get into user management, that is we are going to learn commands that will help us add and remove users and groups. So bring it on...

Before we get into adding new users to our system lets first talk about a command that will be useful if you are a non-root user.

Command: sudo
Syntax: sudo [options] command
Description: sudo allows a permitted user to execute a command as a superuser or another user.

Since the commands to follow need root privileges, if you are not root then don't forget to prefix these commands with sudo command. And yes you'll need to enter the root password in order to execute any command with sudo as root.

Command: useradd
Syntax: useradd [options] username
Description: this command is used for creating new user but is kinda old school.
Lets try to add a new user to our box.
[Note: I'm performing these commands as root user, you'll need root privileges to add a new user to your box. If you aren't root then you can try these commands by prefixing the sudo command at the very beginning of these command like this sudo useradd joe. You'll be prompted for your root password, enter it and you're good to go]

useradd joe

To verify that this command has really added a user to our box we can look at three files that store a users data on a Linux box, which are:

/etc/passwd -> this file stores information about a user separated by colons in this manner, first is login name, then in past there used to be an encrypted password hash at the second place however since the password hashes were moved to shadow file now it has a cross (x) there, then there is user id, after it is the user's group id, following it is a comment field, then the next field contains users home directory, and at last is the login shell of the user.

/etc/group -> this file stores information about groups, that is id of the group and to which group an user belongs.

/etc/shadow -> this file stores the encrypted password of users.

Using our command line techniques we learned so far lets check out these files and verify if our user has been created:

cat /etc/passwd /etc/group /etc/shadow | grep joe

In the above screenshot you can notice an ! in the /etc/shadow, this means the password of this user has not been set yet. That means we have to set the password of user joe manually, lets do just that.

Command: passwd
Syntax: passwd [options] [username]
Description: this command is used to change the password of user accounts.
Note that this command needs root privileges. So if you are not root then prefix this command with sudo.

passwd joe

After typing this command, you'll be prompted password and then for verifying your password. The password won't show up on the terminal.
Now joe's account is up and running with a password.

The useradd command is a old school command, lets create a new user with a different command which is kinda interactive.

Command: adduser
Syntax: adduser [options] user
Description: adduser command adds a user to the system. It is more friendly front-end to the useradd command.

So lets create a new user with adduser.

adduser jane

as seen in the image it prompts for password, full name and many other things and thus is easy to use.

OK now we know how to create a user its time to create a group which is very easy.

Command: addgroup
Syntax: addgroup [options] groupname
Description: This command is used to create a new group or add an existing user to an existing group.

We create a new group like this

addgroup grownups

So now we have a group called grownups, you can verify it by looking at /etc/group file.
Since joe is not a grownup user yet but jane is we'll add jane to grownups group like this:

addgroup jane grownups

Now jane is the member of grownups.

Its time to learn how to remove a user from our system and how to remove a group from the system, lets get straight to that.

Command: deluser
Syntax: deluser [options] username
Description: remove a user from system.

Lets remove joe from our system

deluser joe

Yes its as easy as that. But remember by default deluser will remove the user without removing the home directory or any other files owned by the user. Removing the home directory can be achieved by using the --remove-home option.

deluser jane --remove-home

Also the --remove-all-files option removes all the files from the system owned by the user (better watch-out). And to create a backup of all the files before deleting use the --backup option.

We don't need grownups group so lets remove it.

Command: delgroup
Syntax: delgroup [options] groupname
Description: remove a group from the system.

To remove grownups group just type:

delgroup grownups

That's it for today hope you got something in your head.

Related links

DiscordRAT - Discord Remote Administration Tool Fully Written In Python

Discord Remote Administration Tool fully written in Python3.
This is a RAT controlled over Discord with over 20 post exploitation modules.

Disclaimer:
This tool is for educational use only, the author will not be held responsible for any misuse of this tool.
This is my first project on github as such this project is far from perfect , I will listen to any criticism as long as it is constructive.

Setup Guide:
You will first need to register a bot with the Discord developper portal and then add the bot to the server that you want. Once the bot is created copy the token of your bot and paste it at line 11.
Now on go on discord , go to the settings , go to appearance , scroll to the bottom , and activate "Developer Mode",now go to the server where your bot added right click on the channel where you want the bot to post , click copy ID and finally , paste the ID in the parenthesis in line 99.
Install requirements ("pip3 install -r requirements.txt")
Then if steps above were succesful after launching the python file, or executable , it will post a message on the server with a generated uuid , all that is left to do is posting "!interact " with the given uuid.
Now your bot should be available to use !
Requirements:
Python3,Windows
Compiling to exe (optional):
If you want to compile the bot to exe you can use PyInstaller.
Inside the directory of the bot execute "PyInstaller --onefile --noconsole DiscordRAT.py" or "python3 -m PyInstaller --onefile --noconsole DiscordRAT(NoCV).py (or DiscordRAT.py)"
If an error occured during compiling try to import the discord module "PyInstaller --onefile --noconsole --hidden-import=discord DiscordRAT.py"
Advice:
If you have problems with the installation of win32api or other modules , try installing it in a python virtual environment.
There are two python files one has opencv and webcam related modules the other does not, this has been done because open-cv adds multiple dozens of megabytes to the compiled .exe file.

Download DiscordRAT

via KitPloit

Continue reading

APPLE IPHONE X FACE ID CAN BE HACKED WITH SILICON MASK

Just a week after Apple released its brand new iPhone X on November 3, a team of researchers has claimed to successfully hack Apple's Face ID facial recognition technology with a mask that costs less than $150. They said Apple iPhone x face id can be hacked with silicon mask easily.

apple iPhone x face id hacked
Yes, Apple's "ultra-secure" Face ID security for the iPhone X is not as secure as the company claimed during its launch event in September this year.

"Apple engineering teams have even gone and worked with professional mask makers and makeup artists in Hollywood to protect against these attempts to beat Face ID," Apple's senior VP of worldwide marketing Phil Schiller said about Face ID system during the event.

"These are actual masks used by the engineering team to train the neural network to protect against them in Face ID."

However, the bad news is that researchers from Vietnamese cybersecurity firm Bkav were able to unlock the iPhone X using a mask.

Yes, Bkav researchers have a better option than holding it up to your face while you sleep. Bkav researchers re-created the owner's face through a combination of 3D printed mask, makeup, and 2D images with some "special processing done on the cheeks and around the face, where there are large skin areas" and the nose is created from silicone.

The researchers have also published a proof-of-concept video, showing the brand-new iPhone X first being unlocked using the specially constructed mask, and then using the Bkav researcher's face, in just one go.

"Many people in the world have tried different kinds of masks but all failed. It is because we understand how AI of Face ID works and how to bypass it," an FAQ on the Bkav website said.

"You can try it out with your own iPhone X, the phone shall recognize you even when you cover a half of your face. It means the recognition mechanism is not as strict as you think, Apple seems to rely too much on Face ID's AI. We just need a half face to create the mask. It was even simpler than we ourselves had thought."

Researchers explain that their "proof-of-concept" demo took about five days after they got iPhone X on November 5th. They also said the demo was performed against one of their team member's face without training iPhone X to recognize any components of the mask.

"We used a popular 3D printer. The nose was made by a handmade artist. We use 2D printing for other parts (similar to how we tricked Face Recognition 9 years ago). The skin was also hand-made to trick Apple's AI," the firm said.

The security firm said it cost the company around $150 for parts (which did not include a 3D printer), though it did not specify how many attempts its researchers took them to bypass the security of Apple's Face ID.

It should be noted that creating such a mask to unlock someone's iPhone is a time-consuming process and it is not possible to hack into a random person's iPhone.

However, if you prefer privacy and security over convenience, we highly recommend you to use a passcode instead of fingerprint or Face ID to unlock your phone.

Related links

الاثنين، 18 مايو 2020

Improper Microsoft Patch For Reverse RDP Attacks Leaves 3rd-Party RDP Clients Vulnerable

Remember the Reverse RDP Attack—wherein a client system vulnerable to a path traversal vulnerability could get compromised when remotely accessing a server over Microsoft's Remote Desktop Protocol? Though Microsoft had patched the vulnerability (CVE-2019-0887) as part of its July 2019 Patch Tuesday update, it turns out researchers were able to bypass the patch just by replacing the backward

via The Hacker NewsRelated links

Blockchain Exploitation Labs - Part 3 Exploiting Integer Overflows And Underflows

In part 1 and 2 we covered re-entrancy and authorization attack scenarios within the Ethereum smart contract environment. In this blog we will cover integer attacks against blockchain decentralized applications (DAPs) coded in Solidity.

Integer Attack Explanation:

An integer overflow and underflow happens when a check on a value is used with an unsigned integer, which either adds or subtracts beyond the limits the variable can hold. If you remember back to your computer science class each variable type can hold up to a certain value length. You will also remember some variable types only hold positive numbers while others hold positive and negative numbers.

If you go outside of the constraints of the number type you are using it may handle things in different ways such as an error condition or perhaps cutting the number off at the maximum or minimum value.

In the Solidity language for Ethereum when we reach values past what our variable can hold it in turn wraps back around to a number it understands. So for example if we have a variable that can only hold a 2 digit number when we hit 99 and go past it, we will end up with 00. Inversely if we had 00 and we subtracted 1 we would end up with 99.

Normally in your math class the following would be true:

99 + 1 = 100
00 - 1 = -1

In solidity with unsigned numbers the following is true:

99 + 1 = 00
00 - 1 = 99

So the issue lies with the assumption that a number will fail or provide a correct value in mathematical calculations when indeed it does not. So comparing a variable with a require statement is not sufficiently accurate after performing a mathematical operation that does not check for safe values.

That comparison may very well be comparing the output of an over/under flowed value and be completely meaningless. The Require statement may return true, but not based on the actual intended mathematical value. This in turn will lead to an action performed which is beneficial to the attacker for example checking a low value required for a funds validation but then receiving a very high value sent to the attacker after the initial check. Lets go through a few examples.

Simple Example:

Lets say we have the following Require check as an example:
require(balance - withdraw_amount > 0) ;

Now the above statement seems reasonable, if the users balance minus the withdrawal amount is less than 0 then obviously they don't have the money for this transaction correct?

This transaction should fail and produce an error because not enough funds are held within the account for the transaction. But what if we have 5 dollars and we withdraw 6 dollars using the scenario above where we can hold 2 digits with an unsigned integer?

Let's do some math.
5 - 6 = 99

Last I checked 99 is greater than 0 which poses an interesting problem. Our check says we are good to go, but our account balance isn't large enough to cover the transaction. The check will pass because the underflow creates the wrong value which is greater than 0 and more funds then the user has will be transferred out of the account.

Because the following math returns true:
require(99 > 0)

Withdraw Function Vulnerable to an UnderFlow:

The below example snippet of code illustrates a withdraw function with an underflow vulnerability:

function withdraw(uint _amount){

    require(balances[msg.sender] - _amount > 0);
    msg.sender.transfer(_amount);
    balances[msg.sender] -= _amount;

}

In this example the require line checks that the balance is greater then 0 after subtracting the _amount but if the _amount is greater than the balance it will underflow to a value above 0 even though it should fail with a negative number as its true value.

require(balances[msg.sender] - _amount > 0);

It will then send the value of the _amount variable to the recipient without any further checks:

msg.sender.transfer(_amount);

Followed by possibly increasing the value of the senders account with an underflow condition even though it should have been reduced:

balances[msg.sender] -= _amount;

Depending how the Require check and transfer functions are coded the attacker may not lose any funds at all but be able to transfer out large sums of money to other accounts under his control simply by underflowing the require statements which checks the account balance before transferring funds each time.

Transfer Function Vulnerable to a Batch Overflow:

Overflow conditions often happen in situations where you are sending a batched amount of values to recipients. If you are doing an airdrop and have 200 users who are each receiving a large sum of tokens but you check the total sum of all users tokens against the total funds it may trigger an overflow. The logic would compare a smaller value to the total tokens and think you have enough to cover the transaction for example if your integer can only hold 5 digits in length or 00,000 what would happen in the below scenario?

You have 10,000 tokens in your account
You are sending 200 users 499 tokens each
Your total sent is 200*499 or 99,800

The above scenario would fail as it should since we have 10,000 tokens and want to send a total of 99,800. But what if we send 500 tokens each? Lets do some more math and see how that changes the outcome.

You have 10,000 tokens in your account
You are sending 200 users 500 tokens each
Your total sent is 200*500 or 100,000
New total is actually 0

This new scenario produces a total that is actually 0 even though each users amount is 500 tokens which may cause issues if a require statement is not handled with safe functions which stop an overflow of a require statement.

Lets take our new numbers and plug them into the below code and see what happens:

1. uint total = _users.length * _tokens;
2. require(balances[msg.sender] >= total);
3. balances[msg.sender] = balances[msg.sender] -total;

4. for(uint i=0; i < users.length; i++){
5. balances[_users[i]] = balances[_users[i]] + _value;

Same statements substituting the variables for our scenarios values:

1. uint total = _200 * 500;
2. require(10,000 >= 0);
3. balances[msg.sender] = 10,000 - 0;

4. for(uint i=0; i < 500; i++){
5. balances[_recievers[i]] = balances[_recievers[i]] + 500;

Batch Overflow Code Explanation:

1: The total variable is 100,000 which becomes 0 due to the 5 digit limit overflow when a 6th digit is hit at 99,999 + 1 = 0. So total now becomes 0.

2: This line checks if the users balance is high enough to cover the total value to be sent which in this case is 0 so 10,000 is more then enough to cover a 0 total and this check passes due to the overflow.

3: This line deducts the total from the senders balance which does nothing since the total of 10,000 - 0 is 10,000. The sender has lost no funds.

4-5: This loop iterates over the 200 users who each get 500 tokens and updates the balances of each user individually using the real value of 500 as this does not trigger an overflow condition. Thus sending out 100,000 tokens without reducing the senders balance or triggering an error due to lack of funds. Essentially creating tokens out of thin air.

In this scenario the user retained all of their tokens but was able to distribute 100k tokens across 200 users regardless if they had the proper funds to do so.

Lab Follow Along Time:

We went through what might have been an overwhelming amount of concepts in this chapter regarding over/underflow scenarios now lets do an example lab in the video below to illustrate this point and get a little hands on experience reviewing, writing and exploiting smart contracts. Also note in the blockchain youtube playlist we cover the same concepts from above if you need to hear them rather then read them.

For this lab we will use the Remix browser environment with the current solidity version as of this writing 0.5.12. You can easily adjust the compiler version on Remix to this version as versions update and change frequently.
https://remix.ethereum.org/

Below is a video going through coding your own vulnerable smart contract, the video following that goes through exploiting the code you create and the videos prior to that cover the concepts we covered above:

Download Video Lab Example Code:

Download Sample Code:

CC Labs GitHub

//Underflow Example Code:

//Can you bypass the restriction?

//--------------------------------------------

pragma solidity ^0.5.12;

contract Underflow{
   mapping (address =>uint) balances;

   function contribute() public payable{
        balances[msg.sender] = msg.value;
   }

   function getBalance() view public returns (uint){
return balances[msg.sender];
   }

   function transfer(address _reciever, uint _value) public payable{
   require(balances[msg.sender] - _value >= 5);
   balances[msg.sender] = balances[msg.sender] - _value;

       balances[_reciever] = balances[_reciever] + _value;
   }

}

This next video walks through exploiting the code above, preferably hand coded by you into the remix environment. As the best way to learn is to code it yourself and understand each piece:

Conclusion:

We covered a lot of information at this point and the video series playlist associated with this blog series has additional information and walk throughs. Also other videos as always will be added to this playlist including fixing integer overflows in the code and attacking an actual live Decentralized Blockchain Application. So check out those videos as they are dropped and the current ones, sit back and watch and re-enforce the concepts you learned in this blog and in the previous lab. This is an example from a full set of labs as part of a more comprehensive exploitation course we have been working on.