Direito - Unip - DNA 2,03/08

Direito Unip - DNA 2,3/08 · às 1/18/2024

Are you tired of reading endless news stories about ethical hacking and not really knowing what that means? Let's change that!

This Post is for the people that:

Have No Experience With Cybersecurity (Ethical Hacking)
Have Limited Experience.
Those That Just Can't Get A Break

OK, let's dive into the post and suggest some ways that you can get ahead in Cybersecurity.

I receive many messages on how to become a hacker. "I'm a beginner in hacking, how should I start?" or "I want to be able to hack my friend's Facebook account" are some of the more frequent queries. Hacking is a skill. And you must remember that if you want to learn hacking solely for the fun of hacking into your friend's Facebook account or email, things will not work out for you. You should decide to learn hacking because of your fascination for technology and your desire to be an expert in computer systems. Its time to change the color of your hat 😀

I've had my good share of Hats. Black, white or sometimes a blackish shade of grey. The darker it gets, the more fun you have.

If you have no experience don't worry. We ALL had to start somewhere, and we ALL needed help to get where we are today. No one is an island and no one is born with all the necessary skills. Period.OK, so you have zero experience and limited skills…my advice in this instance is that you teach yourself some absolute fundamentals.

Let's get this party started.

What is hacking?

Hacking is identifying weakness and vulnerabilities of some system and gaining access with it.

Hacker gets unauthorized access by targeting system while ethical hacker have an official permission in a lawful and legitimate manner to assess the security posture of a target system(s)

There's some types of hackers, a bit of "terminology".
White hat — ethical hacker.
Black hat — classical hacker, get unauthorized access.
Grey hat — person who gets unauthorized access but reveals the weaknesses to the company.
Script kiddie — person with no technical skills just used pre-made tools.
Hacktivist — person who hacks for some idea and leaves some messages. For example strike against copyright.

Skills required to become ethical hacker.

Curosity anf exploration
Operating System
Fundamentals of Networking

*Note this sites

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Direito Unip - DNA 2,3/08 · às 6/05/2023

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]

Assign SeEnableDelegationPrivilege to a user
Directory Service Restore Mode (DSRM)
Malicious Security Support Provider (SSP)
DSRMv2
AdminSDHolder
Edit GPO

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! :)

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Direito Unip - DNA 2,3/08 · às 6/05/2023

Just connecting to the service, a 64bit cpu registers dump is received, and so does several binary code as you can see:

The registers represent an initial cpu state, and we have to reply with the registers result of the binary code execution. This must be automated becouse of the 10 seconds server socket timeout.

The exploit is quite simple, we have to set the cpu registers to this values, execute the code and get resulting registers.

In python we created two structures for the initial state and the ending state.

cpuRegs = {'rax':'','rbx':'','rcx':'','rdx':'','rsi':'','rdi':'','r8':'','r9':'','r10':'','r11':'','r12':'','r13':'','r14':'','r15':''}
finalRegs = {'rax':'','rbx':'','rcx':'','rdx':'','rsi':'','rdi':'','r8':'','r9':'','r10':'','r11':'','r12':'','r13':'','r14':'','r15':''}

We inject at the beginning several movs for setting the initial state:

for r in cpuRegs.keys():

code.append('mov %s, %s' % (r, cpuRegs[r]))

The 64bit compilation of the movs and the binary code, but changing the last ret instruction by a sigtrap "int 3"

We compile with nasm in this way:

os.popen('nasm -f elf64 code.asm')

os.popen('ld -o code code.o ')

And use GDB to execute the code until the sigtrap, and then get the registers

fd = os.popen("gdb code -ex 'r' -ex 'i r' -ex 'quit'",'r')

for l in fd.readlines():

for x in finalRegs.keys():

...

We just parse the registers and send the to the server in the same format, and got the key.

The code:

from libcookie import *

from asm import *

import os

import sys

host = 'catwestern_631d7907670909fc4df2defc13f2057c.quals.shallweplayaga.me'

port = 9999

cpuRegs = {'rax':'','rbx':'','rcx':'','rdx':'','rsi':'','rdi':'','r8':'','r9':'','r10':'','r11':'','r12':'','r13':'','r14':'','r15':''}

finalRegs = {'rax':'','rbx':'','rcx':'','rdx':'','rsi':'','rdi':'','r8':'','r9':'','r10':'','r11':'','r12':'','r13':'','r14':'','r15':''}

fregs = 15

s = Sock(TCP)

s.timeout = 999

s.connect(host,port)

data = s.readUntil('bytes:')

#data = s.read(sz)

#data = s.readAll()

sz = 0

for r in data.split('\n'):

for rk in cpuRegs.keys():

if r.startswith(rk):

cpuRegs[rk] = r.split('=')[1]

if 'bytes' in r:

sz = int(r.split(' ')[3])

binary = data[-sz:]

code = []

print '[',binary,']'

print 'given size:',sz,'bin size:',len(binary)

print cpuRegs

for r in cpuRegs.keys():

code.append('mov %s, %s' % (r, cpuRegs[r]))

#print code

fd = open('code.asm','w')

fd.write('\n'.join(code)+'\n')

fd.close()

Capstone().dump('x86','64',binary,'code.asm')

print 'Compilando ...'

os.popen('nasm -f elf64 code.asm')

os.popen('ld -o code code.o ')

print 'Ejecutando ...'

fd = os.popen("gdb code -ex 'r' -ex 'i r' -ex 'quit'",'r')

for l in fd.readlines():

for x in finalRegs.keys():

if x in l:

l = l.replace('\t',' ')

try:

i = 12

spl = l.split(' ')

if spl[i] == '':

i+=1

print 'reg: ',x

finalRegs[x] = l.split(' ')[i].split('\t')[0]

except:

print 'err: '+l

fregs -= 1

if fregs == 0:

#print 'sending regs ...'

#print finalRegs

buff = []

for k in finalRegs.keys():

buff.append('%s=%s' % (k,finalRegs[k]))

print '\n'.join(buff)+'\n'

print s.readAll()

s.write('\n'.join(buff)+'\n\n\n')

print 'waiting flag ....'

print s.readAll()

print '----- yeah? -----'

s.close()

fd.close()

s.close()

Continue reading

Direito - Unip - DNA 2,03/08

quinta-feira, 18 de janeiro de 2024

How To Start | How To Become An Ethical Hacker

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quarta-feira, 17 de janeiro de 2024

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segunda-feira, 5 de junho de 2023

Thousand Ways To Backdoor A Windows Domain (Forest)

Ways to backdoor a domain

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Forensics

Lessons learned

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