NTDS.dit files can contain entries relative to principals belonging to other trusted domains (intra- or extra-forest). Naturally, foreign principals passwords are not stored in the local domain's NTDS.dit.
When parsing these files, secretsdump outputs those principals anyway, with an empty password as their NT hash. It would be better to filter them out from the output to not mislead the user (many times I have been surprised at first to see an enabled T0 user with an empty password).
Solution
This PR aims to fix this by filtering out foreign principals based on the value of the instanceType attribute. Through trial and error, I have observed that local principals have the bit 0x4 ("The object is writable on this directory.") enabled in this attribute, while foreign ones do not.
Example
This issue can be observed on the GOAD lab, for instance when dumping the NTDS.dit file of the winterfell.north.sevenkingdoms.local domain controller. Secretsdump's output will be as such. Note the presence of many foreign principals with an empty password as their NT hash, such as a duplicated Administrator user.
After applying this PR, the result is the following. Note that the foreign principals are not present anymore.
$ secretsdump.py -ntds ntds.dit -system system -user-status -just-dc-ntlm LOCAL
Impacket v0.12.0.dev1+20240523.75507.15eff880 - Copyright 2023 Fortra
[*] Target system bootKey: 0x6457f466e87a6ec861b680d31c7a6759
[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Searching for pekList, be patient
[*] PEK # 0 found and decrypted: 8b7862def60e442f7425b23f1bc78670
[*] Reading and decrypting hashes from ntds.dit
Administrator:500:aad3b435b51404eeaad3b435b51404ee:dbd13e1c4e338284ac4e9874f7de6ef4::: (status=Enabled)
Guest:501:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0::: (status=Disabled)
vagrant:1000:aad3b435b51404eeaad3b435b51404ee:e02bc503339d51f71d913c245d35b50b::: (status=Enabled)
WINTERFELL$:1001:aad3b435b51404eeaad3b435b51404ee:ffc37752d112b06cfad97941c7ac10fc::: (status=Enabled)
krbtgt:502:aad3b435b51404eeaad3b435b51404ee:44e1f85ccf1935db45f88b71f8f96096::: (status=Disabled)
CASTELBLACK$:1104:aad3b435b51404eeaad3b435b51404ee:0c793a8a77ad8dda4b647454f93ef3dc::: (status=Enabled)
SEVENKINGDOMS$:1105:aad3b435b51404eeaad3b435b51404ee:7bf01d9b9a8d6520689556fbc1af5589::: (status=Enabled)
arya.stark:1110:aad3b435b51404eeaad3b435b51404ee:4f622f4cd4284a887228940e2ff4e709::: (status=Enabled)
eddard.stark:1111:aad3b435b51404eeaad3b435b51404ee:d977b98c6c9282c5c478be1d97b237b8::: (status=Enabled)
catelyn.stark:1112:aad3b435b51404eeaad3b435b51404ee:cba36eccfd9d949c73bc73715364aff5::: (status=Enabled)
robb.stark:1113:aad3b435b51404eeaad3b435b51404ee:831486ac7f26860c9e2f51ac91e1a07a::: (status=Enabled)
sansa.stark:1114:aad3b435b51404eeaad3b435b51404ee:b777555c2e2e3716e075cc255b26c14d::: (status=Enabled)
brandon.stark:1115:aad3b435b51404eeaad3b435b51404ee:84bbaa1c58b7f69d2192560a3f932129::: (status=Enabled)
rickon.stark:1116:aad3b435b51404eeaad3b435b51404ee:7978dc8a66d8e480d9a86041f8409560::: (status=Enabled)
hodor:1117:aad3b435b51404eeaad3b435b51404ee:337d2667505c203904bd899c6c95525e::: (status=Enabled)
jon.snow:1118:aad3b435b51404eeaad3b435b51404ee:b8d76e56e9dac90539aff05e3ccb1755::: (status=Enabled)
samwell.tarly:1119:aad3b435b51404eeaad3b435b51404ee:f5db9e027ef824d029262068ac826843::: (status=Enabled)
jeor.mormont:1120:aad3b435b51404eeaad3b435b51404ee:6dccf1c567c56a40e56691a723a49664::: (status=Enabled)
sql_svc:1121:aad3b435b51404eeaad3b435b51404ee:84a5092f53390ea48d660be52b93b804::: (status=Enabled)
[*] Cleaning up...
One thing to be aware of: when looking at the instanceType attribute of accounts local to this domain on a live DC, we can observe that some of them have their instanceType attribute empty. However, in the NTDS.dit itself, this value is 4 as expected:
Hi!
Problem
NTDS.dit files can contain entries relative to principals belonging to other trusted domains (intra- or extra-forest). Naturally, foreign principals passwords are not stored in the local domain's NTDS.dit.
When parsing these files, secretsdump outputs those principals anyway, with an empty password as their NT hash. It would be better to filter them out from the output to not mislead the user (many times I have been surprised at first to see an enabled T0 user with an empty password).
Solution
This PR aims to fix this by filtering out foreign principals based on the value of the
instanceTypeattribute. Through trial and error, I have observed that local principals have the bit0x4("The object is writable on this directory.") enabled in this attribute, while foreign ones do not.Example
This issue can be observed on the GOAD lab, for instance when dumping the NTDS.dit file of the
winterfell.north.sevenkingdoms.localdomain controller. Secretsdump's output will be as such. Note the presence of many foreign principals with an empty password as their NT hash, such as a duplicatedAdministratoruser.After applying this PR, the result is the following. Note that the foreign principals are not present anymore.
One thing to be aware of: when looking at the
instanceTypeattribute of accounts local to this domain on a live DC, we can observe that some of them have theirinstanceTypeattribute empty. However, in the NTDS.dit itself, this value is4as expected:As such, the filtering works correctly.
Cheers!
PS: thanks to @vletoux for https://github.com/vletoux/ADSecrets, very useful when diving into NTDS internals 🙂