Questions tagged [kerberos]

Kerberos is a network authentication protocol designed to allow nodes, communicating over a non-secure network, to prove their identity to one another in a secure manner.

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User authentication: In HTTP Server vs. in Web Application

Management decided to switch the authentication-backend from LDAP to Kerberos as LDAP is deemed "obsolete and insecure". Also they want to switch from Apache to nginx for "performance ...
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Kerberos tickets for service accounts and NFSv4 id mapping

I have a Synology NAS that I'm trying to access over NFS from a couple of systems running archlinux (a laptop and a server). I'd like to get NFSv4 id mapping working so that I don't have to align the ...
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What exactly could we get as an attacker if Kerberos Pre-Authentication is disabled?

I'm learning about how Kerberos and it's common exploits work and I'm a little confused. In this video explaining the process we see that at one of the earlier points the user is provided with two ...
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Is it possible to use Kerberos for SSO in a SaaS application?

If I have a webapplication in my internal Microsoft Windows network I'm aware that I can use the kerberos protocol to make a Single Sign on (SSO) into this application with the web browser. Is it a ...
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NTLM Modern usage

I understand that Kerberos is the recent authentication protocol used in windows environment and that NTLM is still supported for interoperability only. I want to know in non domain environments,if i ...
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Is kerberos unconstrained delegation partially safer than constrained delegation?

When you're using unconstrained delegation, a service A is allowed to authenticate as the user B to any other service. This happens because the user B sends its TGS along with its TGT to the service A,...
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Are there any reasons for Kerberos being based on symmetric cryptography?

Kerberos is an authentication protocol that is famously built using only symmetric ciphers. As a direct result of this, there are several attacks possible, such as AS-REP Roasting AS-REQ Roasting ...
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234 views

Manually creating computer account and SPN's in Kerberos (krb5) keytab file for Window Active Directory domain

Lots of articles on the net describes how you can join a Linux box to a Windows Active Directory domain, some using "realmd", some using samba and so forth. Others describe how you can do things ...
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Does Kerberos authentication handle DNS names the same way between Windows 7 and Windows 10?

Recently, we migrated from Windows 7 to Windows 10 and during that migration, we progressively ran into some issues with our NAS device. To be more precise, we progressively noticed some tcp socket ...
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Caching TGT from a browser

I'm playing around with Kerberos SSO. As experimented so far, When I open a web app that is configured with Kerberos, from the browser, it prompts me for the username and credential, once I enter, I'...
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111 views

How does the browser know windows logged in user id or Kerberos TGT?

My organization uses SSO for its applications i.e. Once a user logs into his Windows 10 workstation, he accesses his web application without login. I was informed that the web applications uses NetIQ ...
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629 views

Browser not generating kerberos ticket

Firstly, please apologise me if I'm still confused about stuff here, Kerberos auth is quite the complex issue for a java dev So, I have the following scenario: A suite of webapps which use kerberos ...
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60 views

Kerberos over http documentation

The NTLM over HTTP documentation can be found here https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-ntht/f09cf6e1-529e-403b-a8a5-7368ee096a6a Where is the Kerberos over HTTP official ...
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134 views

How to obtain Service Tickets (TGS) for Service Accounts with no SPNs (ServicePrincipalName) set?

The first step in a kerberoasting attack is to discover Service Accounts via AD enumeration. One way to do so is searching LDAP for any registered SPNs (Service Principal Names). However, from my ...
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How to decode kerberos tickets on wireshark? [closed]

It has been two days in a row that I spend hours trying to decrypt kerberos traffic using wireshark. For learning purposes, I want to be able to read the encrypted parts of tickets and authenticators ...
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Does kerberos support a grace period in password changes?

The principles are programs instead of human. I want to rotate their password regularly, using random generated password, and then deliver the new password to the programs. I have a mechanism to make ...
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Is SQL auth over windows auth a red flag?

I'm working on something where using windows authentication to SQL server is difficult if not impossible. My team member is adamant that using SQL auth is much more difficult to manage and is a major ...
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79 views

Is there any existing attempted implementation of GSS-API/SPNEGO/GSS-SPNEGO for anything other than Kerberos / NTLM?

I'm aware that SPNEGO is de-facto only used in the wild for Kerberos or NTLM. Is there any research / academic / educational example on how it can be also used for other mechanisms as well?
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Kerberos Encryption and Decryption

Hacker is able to sniff the traffic between the editor, the KDC and the network scanner during the key exchange. Is he/she able to decrypt the sniffed data key?
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Kerberos Authentication : Client authentication only

I am currently implementing a way to authenticate using Kerberos mechanism. Then only explanation have is "SSO using Kerberos". I know technically how works Kerberos (Keytab, SPNEGO, Token, KDC, SPN)...
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119 views

Bruteforcing via port 88 on MacOS

Macos has open port 88 by default. Is it possible to check validity of the password via this port from Linux and how? If the vncserver is active, it is possible to know also the username (by ...
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How much time is needed for bruteforce kerberos/ntlm? [closed]

How much time does an attacker need for full bruteforce on typical complexity password policy given either: kerberos ticket/ as req or Ntlm transaction This depends on the algorithm used (rc4/aes). ...
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In Kerberos authentication protocol, why is the TGT encrypted using the user's key Ka?

When the user first logs in, he fetches his TGT from the KDC along with the session key. I get why Sa (session key) is encrypted with Ka (user's key). But why is TGT also encrypted with Ka. TGT is ...
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How to retrieve Kerberos Service tickets?

I am learning Kerberoasting see below are my steps that I am following. Step:1. Attacker will find the SPN's Step:2. After identifying we will request for TGS for that SPN. This is the script for ...
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What is possible with a non-administrative users Ticket Granting Ticket and/or NTLM hash?

During a penetration test, if a users NTLM hash or a valid Kerberos TGT is compromised, what attacks are possible if the user is not an administrator on any (in scope) workstations? For instance, it ...
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Is there a replay cache in Kerberos 4?

Does Kerberos version 4 support replay cache like in V5 - a cache that prevents replay attacks which occur within the clock skew, so the TGS knows a duplicate packet has arrived ?
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170 views

Kerberos replay attack within allowed range - authenticator won't prevent it?

In kerberos protocol the client, after receiving a ticket to the TGS server, sends a request to the TGS and adds an authenticator to the request. What if an attacker performs a replay attack within ...
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Use Kerberos Golden Ticket with Metasploit

Having compromised a domain controller during testing, I now wish to create persistent domain admin access. Also, operational security is important for me as I don't want to be logging into netowkr ...
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Why Realm_tgs is needed in Kerberos v5 Protocol? (Step 2)

In msg.2 the AS sends Realm_c, ID_c Ticket_tgs, K_c-tgs, times, N1, Real_tgs, ID_tgs encrypted with E_k_c. I can't understand why Real_tgs is included if AS and TGS are on the same machine.
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691 views

How to crack AES-based Kerberos TGS tickets (Kerberoasting)?

All material I can find is related to RC4-based Kerberos TGS tickets, since these are easier to crack to obtain the service account's password. However, I want to attempt to crack AES-based Kerberos ...
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1answer
127 views

Certificates for autoscaling internal networks?

A public website with an SSL certificate makes use of a certificate and CA in order to establish trust between the server and client. How is the same thing typically implemented on private networks, ...
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450 views

Can Kerberos encrypt network traffic between servers?

Working in a coporate environment, which uses Active Directory, I overheard someone making a comment stated the Kerberos protcol can be used to encrypt network traffic between Windows servers. Can ...
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Kerberos Attacks Questions

It's amazing how many "Attacks on Kerberos" articles exist out there and almost none really explains the small details. My guess is that usually they assume it's basic knowledge and sometimes, they ...
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What are the flaws in this security protocol between client and server? [closed]

Here is my security protocol for the use of a service provided by server. It utilises a symmetric key: Client requests to use a service Server sends back nonce Client sends back nonce encrypted with ...
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Questions regarding pass the ticket

In the blackhat talk by Gentikwiki on Mimikatz back in 2014, he mentioned that you can pass the service ticket also, but i am unable to replicate it in a lab. It throws an access denied. Passing the ...
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Kerberos Protocol Centralized Server

If a small company is expanding with various branches across the country, how would the kerberos centralized server be configured? Are the new users assigned new ticket granting servers or are they ...
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Why the need for user ID in ticket AND authenticator (Kerberos)?

I am currently learning about Kerberos. Why the following in Kerberos v4: Client -> Service : Ticket_Service || Authenticator_Client where Ticket_Service: E(K_S, [K_C,S || ID_C || ...]) and ...
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398 views

Kerberos unconstrained delegation for user

I've noticed that there is an option to set "Trust this user for delegation to any service" that can be set for service users. I've read a lot about unconstrained delegation with regards to computers ...
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2k views

A replay attack was detected (4649) & Exchange Healthmailbox

We received alarms for this in our SIEM today. I believe it is expected and just "noise". The alarm was triggered immediately after Exchange cleared the ThrottlingConfig.log. I know Exchange ...
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Mimikatz /rc4 argument for pass-the-ticket?

I'm studying how pass-the-ticket works using Mimikatz, i.e., forged Silver and Golden Kerberos tickets. The command usually takes the form (Golden tickets): kerberos::golden /sid:SID /domain:DOMAIN /...
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Kerberos three transactions — why not just use two?

I have read the description of Kerberos at sites like this very informative one: http://www.roguelynn.com/words/explain-like-im-5-kerberos/ I think I understand generally how it works: User ...
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485 views

Reasons to transition Kerberos secured web applications to OAuth2/OpenId

We have five internal web applications written in Java / AngularJs that are secured via Kerberos/ Spnego ( Spring Security implementation) . We are looking to transition these apps to AWS ( EBS) . ...
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Risks for implementing single sign on

I'm working with an organization that's integrating a lot of apps with LDAP in a Windows environment. They are doing a good job of implementing least privilege, so there aren't a lot of scenarios ...
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How do I lookup the UID of a domain user?

I'm playing with golden ticket (mimikatz) kerberos::golden /domain:vln2012.local /sid:S-1-5-21-3871786346-2057636518-1625323419 /rc4:8ad36fef31e071eac7ab9d54a093cb54 /user:user1 /id:1109 /groups:500,...
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LDAPS needed when using Kerberos?

In the past two years i built up a small office with more needs every day. At some point i needed a DC with Kerberos. All Server (CentOS besides the DCs) communicate over Kerberos with the DC. Since ...
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How to update authorization information in a KDC dynamically?

I wish to add Kerberos authentication and authorization into a project that has a service server that interacts with a Hadoop cluster that has some users and permissions. As far as I know, the KDC ...
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Does Windows Authentication Use Secured Connection

I am writing a .NET Web API that will be used in an enterprise environment where users authentication themselves using their active directory credentials, so I am using "Windows Authentication" in IIS ...
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796 views

Kerberos and brute-force attacks

Suppose that I am the administrator of a system that uses Kerberos and password authentication. How can I make brute-force attacks on user’s passwords by an attacker who can capture network traffic ...
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706 views

Web API authentication with Kerberos

We are implementing a web application that uses Kerberos for authentication. In the browser there is no concerns, so it works perfect. Now we need to supply a subset of web application services via ...
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877 views

Password reset for AD RODC-specific krbtgt_xxxxx accounts

While there's a lot of information [1], [2], [3] about resetting the password for the regular krbtgt account, but I haven't yet found a clear suggestion about RODC-specific krbtgt_xxxxx accounts. ...