IKATAN ALUMNI SMPN 233 JAKARTA: Agustus 2020

31 Agu 2020

OpenVAS

"OpenVAS stands for Open Vulnerability Assessment System and is a network security scanner with associated tools like a graphical user front-end. The core is a server component with a set of network vulnerability tests (NVTs) to detect security problems in remote systems and applications." read more...

Website: http://www.openvas.org

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30 Agu 2020

Thousand Ways To Backdoor A Windows Domain (Forest)

When the Kerberos elevation of privilege (CVE-2014-6324 / MS14-068) vulnerability has been made public, the remediation paragraph of the following blog post made some waves:
http://blogs.technet.com/b/srd/archive/2014/11/18/additional-information-about-cve-2014-6324.aspx

"The only way a domain compromise can be remediated with a high level of certainty is a complete rebuild of the domain."

Personally, I agree with this, but .... But whether this is the real solution, I'm not sure. And the same applies to compromised computers. When it has been identified that malware was able to run on the computer (e.g. scheduled scan found the malware), there is no easy way to determine with 100% certainty that there is no rootkit on the computer. Thus rebuilding the computer might be a good thing to consider. For paranoids, use new hardware ;)

But rebuilding a single workstation and rebuilding a whole domain is not on the same complexity level. Rebuilding a domain can take weeks or months (or years, which will never happen, as the business will close before that).

There are countless documented methods to backdoor a computer, but I have never seen a post where someone collects all the methods to backdoor a domain. In the following, I will refer to domain admin, but in reality, I mean Domain Admins, Enterprise Admins, and Schema Admins.

Ways to backdoor a domain

So here you go, an incomplete list to backdoor a domain:

Create a new domain admin user. Easy to do, easy to detect, easy to remediate
Dump password hashes. The attacker can either crack those or just pass-the-hash. Since KB2871997, pass-the-hash might be trickier (https://technet.microsoft.com/library/security/2871997), but not impossible. Easy to do, hard to detect, hard to remediate - just think about service user passwords. And during remediation, consider all passwords compromised, even strong ones.
Logon scripts - modify the logon scripts and add something malicious in it. Almost anything detailed in this post can be added :D
Use an already available account, and add domain admin privileges to that. Reset its password. Mess with current group memberships - e.g. http://www.exploit-db.com/papers/17167/
Backdoor any workstation where domain admins login. While remediating workstations, don't forget to clean the roaming profile. The type of backdoor can use different forms: malware, local admin, password (hidden admin with 500 RID), sticky keys, etc.
Backdoor any domain controller server. For advanced attacks, see Skeleton keys
Backdoor files on network shares which are commonly used by domain admins by adding malware to commonly used executables - Backdoor factory
Change ownership/permissions on AD partitions - if you have particular details on how to do this specifically, please comment
Create a new domain user. Hide admin privileges with SID history. Easy to do, hard to detect, easy to remediate - check Mimikatz experimental for addsid
Golden tickets - easy to do, hard to detect, medium remediation
Silver tickets - easy to do, hard to detect, medium/hard remediation
Backdoor workstations/servers via group policy

HKEY_LOCAL_MACHINE\ Software\ Microsoft\ Windows\ CurrentVersion\ RunOnce,
scheduled tasks (run task 2 years later),
sticky-keys with debug

Backdoor patch management tool, see slides here

[Update 2017.01.10]

Other tricks

The following list does not fit in the previous "instant admin" tips, but still, it can make the attackers life easier if their primary foothold has been disabled:

Backdoor recent backups - and when the backdoor is needed, destroy the files, so the files will be restored from the backdoored backup
Backdoor the Exchange server - get a copy of emails
Backdoor workstation/server golden image
Change permission of logon scripts to allow modification later
Place malicious symlinks to file shares, collect hashes via SMB auth tries on specified IP address, grab password hashes later
Backdoor remote admin management e.g. HP iLO - e.g. create new user or steal current password
Backdoor files e.g. on shares to use in SMB relay
Backdoor source code of in-house-developed software
Use any type of sniffed or reused passwords in new attacks, e.g. network admin, firewall admin, VPN admin, AV admin, etc.
Change the content of the proxy pac file (change browser configuration if necessary), including special exception(s) for a chosen domain(s) to use proxy on malicious IP. Redirect the traffic, enforce authentication, grab password hashes, ???, profit.
Create high privileged users in applications running with high privileges, e.g. MSSQL, Tomcat, and own the machine, impersonate users, grab their credentials, etc. The typical pentest path made easy.
Remove patches from servers, change patch policy not to install those patches.
Steal Windows root/intermediate CA keys
Weaken AD security by changing group policy (e.g. re-enabling LM-hashes)

Update [2015-09-27]: I found this great presentation from Jakob Heidelberg. It mentions (at least) the following techniques, it is worth to check these:

Microsoft Local Administrator Password Solution
Enroll virtual smart card certificates for domain admins

Forensics

If you have been chosen to remediate a network where attackers gained domain admin privileges, well, you have a lot of things to look for :)

I can recommend two tools which can help you during your investigation:

Lessons learned

But guess what, not all of these problems are solved by rebuilding the AD. One has to rebuild all the computers from scratch as well. Which seems quite impossible. When someone is creating a new AD, it is impossible not to migrate some configuration/data/files from the old domain. And whenever this happens, there is a risk that the new AD will be backdoored as well.

Ok, we are doomed, but what can we do? I recommend proper log analysis, analyze trends, and detect strange patterns in your network. Better spend money on these, than on the domain rebuild. And when you find something, do a proper incident response. And good luck!

Ps: Thanks to Andrew, EQ, and Tileo for adding new ideas to this post.

Check out the host backdooring post as well! :)

More information

Hacking Freemium Games - The Evolution Of PC Game Cheating

This post is going to be a rather strange post compared to previous ones. But bear with me, in the middle of the post you will see why this post fits the IT security topic.

I'm also terribly sorry for not posting recently, but I was busy with my SPSE and SLAE certification. Both are recommended for Python and Assembly noobs like me. But back to this post.

A little bit of history

Cheating in games started as help for game testers. By using invincibility or infinite ammo testers were able to test the game quicker, which meant less money spent on testing. I personally use cheat codes in games, depending on my mood. Sometimes it feels good to slash all the opponents while I'm invincible, sometimes it is more fun to play the game without cheats. One can argue whether cheating in games is OK or not, but I believe it depends, there is no black or white. But one thing is for sure, it is part of the gaming industry. There is huge demand for cheats. There were even cheat books printed on paper...

The different types of cheats (on PC)

There are different types of cheats in PC gaming. Following is a noncomplete list of these cheats:

Cheat codes

The good old IDDQD type of cheats. These are left in the game by the developers intentionally. Nothing interesting here.

Edit memory

This is my favorite. I will talk about this at the end of the post. Whenever a user launches a new program, the program's whole memory is accessible (read/write) to every other program launched by the user. And since the memory stores the current game state (health, ammo, armor, etc.), these values can be changed easily. In the good old times, there were POKE commands to do this cheats, and the memory address to write into was published by people who found where the game stores the most critical states about the game.

Code injection

This is like patching the game code. For example, one can change the "DEC (pointer to your current health)" instruction with NOP (do nothing), thus becoming invincible. In multi-player cheats, there is the aimbot to help you aim at enemies, wallhack to see through the wall, increase hitbox of the enemy for smoother hit, or in MMORPGs, one can write macros to collect items while the player is not online. I would say the so-called "trainers" more or less fit into this category and the previous one.

Saved game editor

The first time a kid meets a hex-editor (just like the co-author of this blog did with SIM City when he was 10 years old - David). It can teach a lot about file structures, the hexadecimal numeral system, etc. Fun times.

Hacking game server

Not very common, but even more fun. Warning: endless trolling possibilities in multi-player games ahead :) How to hack a game server? Well, I think this might deserve another full blog post ...

Network traffic hacking

One last necessary type of cheating is to modify network traffic between the client and the game server. AFAIK SSL is not universal in gaming, so stunnel is not needed for this hack, but ettercap can help in changing the communication.

Why cheating becomes more critical (and challenging)?

Now in the age of in-app-payments, the game creators are no longer thinking about cheats as funny things but something to be destroyed to the ground. Because cheating decreases its revenue. Or not. At least they think it does. To quote Wikipedia here, "cheating in such games is nonetheless a legal grey area because there are no laws against modifying software which is already owned, as detailed in the Digital Millennium Copyright Act."

A lot of online games include anti-cheating components like PunkBuster, nProtect GameGuard, or Valve Anti-Cheat. This whole cheating/anti-cheating industry is the same as the virus/anti-virus industry. A cat and mouse game.

Freemium games

If you have not played with "freemium" games, you should watch South Park season 18, episode 6. - "Freemium Isn't Free." If you did play with freemium games, you definitely have to watch it :) There are many problems with freemium games. It is free to install, free to play. The first 3-4 hours might be fun to play. But after that, it turns out it is impossible to advance in the game without paying money for it. And by spending cash, I mean spending a LOT! Let's have a look at today's example, an arcade racing video game.

For 99.99 USD, you can get 3 000 000 credit. For almost double the price of a new PC game, you can get these credits. In this particular game, I estimate one have to play ~6-24 hours constantly to get this amount of credit. But by playing ~6 hours, I mean 6 hours without progress in the game! Kind of boring. And what do you get from 3 000 000 credit? You can buy one of the most expensive cars, but can't tune them fully. You have to play more (without progress) or buy more. But guess what, there are more cars you can't buy by only playing the game. Those are only available via in-app-purchase.

Even though the player has 58 765 533 credits, it is not possible to buy this car. Only available through real money.

So, what are your possibilities? You are either Richie Rich, and can afford the money to buy these. Or you can be insane, and try to play the game without in-app-purchase. Or give up the game and try another freemium ... Or, you can try to hack the game!

Hack all the freemium games!

Although I was not playing this racing game from day one, I was able to witness the evolution of the cheats against this game. The cheats which worked in one day was not working one month later. The game is continuously updated to defeat the newly published cheats.

Noob start

So, I want to hack this game, what is the first thing a noob like me does? ~~Bing it!~~ Google it!

From the first page result, let's check this tool:

While trying to download that, I just have to give my email address to spammers, or my mobile number will be subscribed to premium rate text messages. What fun.

Another "cheat" program will install malware/adware on your computer. Never ever try these programs. They are fake 99% of the time and after installing those you will have another problem, not just how to hack freemium games.

Beginners start - Cheat engine

When I first heard about hacking games in memory, I visualized hours of OllyDBG/ImmunityDBG/(insert your favorite Windows debugger here). It turned out, there are some specialized tools to help you with cheating the game. No assembly knowledge required. My favourite tool is CheatEngine. I highly recommend to download it and spend 10 minutes to get past the built-in tutorial levels to get a feeling about this tool. It's super duper awesome.

When I first tried to hack this game myself, I scanned the memory for my actual credit and tried to change that, no luck. Keep reading, you will see what happened.

The second cheat I tried with cheat engine was something like this:

Start the game, play the first level, and check how many credits is paid for winning the race. Pro tip: use dual display for full-screen game cheating.
Restart the same level, attach Cheat Engine to the game's process
Scan the memory for the same value at the beginning of the race
Scan the memory for the same value at the end of the game. The intersect of the first and second scan includes the real value where the credit is stored for winning the race.
Change the values (both the real one and some false positives) to something big
Watch the game to crash
Be amazed at the money you received

Nowadays, most of the cheats on YouTube does not work. Except for these kind of cheats. I don't want to recreate that tutorial, so you should watch it first then come back.

Are you back? Great. Do you have any idea what have you just seen? No? Well, in this case, don't try this at home. Copy-pasting assembly code from random internet posts and running on your computer is always a bad idea. It is precisely as risky as downloading free programs from random internet sites.

Although I have not seen people trolling others with this cheat engine type of shellcode, I think the time will come when these will be turned into something terrible. These shellcodes might work, or might harm your computer. The good news is, we can have a look at the code and analyze it.

When you open CheatEngine and try to define a new custom type, you are greeted with a skeleton assembly code. I don't want to detail what all the skeleton code does, let's just focus on the difference between the skeleton code and the code used in the video. This is the "decrypt function":

xor eax, 0baadf00d
rol eax, 0e

What does it mean? The actual credit is encrypted in memory. If you want to scan it in memory, you won't be able to find it. But! The encryption is rotating the value to the right (ROR) with 0xE (14 in decimal), and after that, it is XOR-ed with 0xbaadf00d. Decrypting it is the inverse of the functions in reverse order (in this particular case, the order does not matter, but that's not the point). The inverse function of XOR is XOR, and the inverse function of ROR (rotate right) is ROL (rotate left). Now that we analyzed the assembly code, we can be sure that it is safe to execute. Just follow the video and see your coins falling from the sky. For free. In a freemium game. Have fun!

Encrypt memory - applications at financial institutions

Another exciting thing is that I don't recall any thick client applications in the financial industry encrypting the values in memory. And I agree, there are more significant problems with thick client applications than not encrypting the essential values in memory. But still, some thick client applications are regularly updated, maintained. Maybe it is a good idea to encrypt the values in memory. It will make attackers' life harder. Not impossible, but harder. Perhaps the developers of these applications should learn from the gaming industry (or from malware developers for that matter) because it is a shame that an arcade racing game or an FPS is protected better than an application responsible for transacting millions of dollars. Just think about the RAM scraping malware stealing millions of credit card data ...

Moral of the story

Cheating is part of the gaming history, and the freemium games are trying to take away the cheats from the gamers because they want money. Thanks to CheatEngine and some clever hacks, these programs can be still beaten. And guess what, there is CheatEngine for Android - although it did not work for me on the latest Android. And sometimes, hacking all kinds of applications can be more comfortable with CheatEngine, compared to traditional debuggers.

Also, always check the code before executing it! And when you find something cool, publish it, so everyone could enjoy the games!

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