Implications of allowing Windows clients to use NTLMv1?

Posted by Boden on Server Fault See other posts from Server Fault or by Boden
Published on 2009-07-29T23:31:47Z Indexed on 2012/10/04 3:40 UTC
Read the original article Hit count: 415

Filed under:

Windows

|

security

|

authentication

|

group-policy

|

ntlm

I have a web application that I'd like to authenticate to using pass-through NTLM for SSO. There is a problem, however, in that NTLMv2 apparently will not work in this scenario (without the application storing an identical password hash).

I enabled NTLMv1 on one client machine (Vista) using its local group policy: Computer->Windows Settings->Security Settings->Network Security: LAN Manager authentication level. I changed it to Send LM & NTLM - use NTLMv2 session security if negotiated.

This worked, and I'm able to login to the web application using NTLM. Now this application would be used by all of my client machines... so I'm wondering what the security risks are if I was push this policy out to all of them (not to the domain controller itself though)?

© Server Fault or respective owner

Related posts about Windows

Server 2012 DFS New Member Issue

as seen on Server Fault - Search for 'Server Fault'
I am trying to add a new member to our DFS topology. We have 3 DCs (VMs - VMware) running Windows server 2012, two servers are located in or Primary site and the third at our DR site. Currently the two servers at our primary site are currently replicating DFS (full mesh) and are working fine. I have… >>> More
error in IIS7 but not on IIS6

as seen on Server Fault - Search for 'Server Fault'
I have a website that is we are now deploying to windows 2008 servers that has worked in the past on IIS6 without a problem. It is using .net 2 framework. Most of the website works. Just when we create a screen report over a certain size on the server we get this error. Event code: 3005 Event… >>> More
error in IIS7 but not on IIS6

as seen on Server Fault - Search for 'Server Fault'
I have a website that is we are now deploying to windows 2008 servers that has worked in the past on IIS6 without a problem. It is using .net 2 framework. Most of the website works. Just when we create a screen report over a certain size on the server we get this error. Event code: 3005 Event… >>> More
Microsoft Management Console stops working when I add snap-in to it

as seen on Super User - Search for 'Super User'
I have Windows 7 Ultimate OS. I'm opening mmc.exe as administrator and trying add Certificates or any other snap-in, then while loading that snap-in MMC breaks and displays following message and after that it closes automatically once I click on close button on that message. What could be the problem… >>> More
Handling keyboard and mouse input (Win API)

as seen on Game Development - Search for 'Game Development'
There is a number of ways to catch mouse or keyboard under Windows. So I tried some of them, but every of them has some advantages and drawbacks. I want to ask you: Which method do use? I've tried these: WM_KEYDOWN/WM_KEYUP - Main disadvantage is that, I can't distinguish between left and right-handed… >>> More

Related posts about security

sudo apt-get update errors

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
Here is what I get on my terminal when running sudo apt-get update errors. I dont know if the issue is from my sources.list or my proxy setup(have not made any changes to proxies). Thank you for any help in advanced. Ign http://security.ubuntu.com oneiric-security Release.gpg Ign http://security… >>> More
The Security-Developer Gap: Why IT Security Can't Fix Your Security Problems Alone

as seen on Devx - Search for 'Devx'
Two well-known white hats explain how hackers take advantage of security holes left by enterprise application developers. >>> More
The Security-Developer Gap: Why IT Security Can't Fix Your Security Problems Alone

as seen on Internet.com - Search for 'Internet.com'
Two well-known white hats explain how hackers take advantage of security holes left by enterprise application developers. >>> More
StackOverFlowError while creating Mac object on AS400/Java

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello all, I am a newbie to AS400-Java programming. I am trying to create my first program to test the implementation of Message Authentication Code (MAC). I am trying to use the HMACSHA1 hash function. My (Java 1.4) program runs fine on a dev box (V5R4).But fails terribly on the QA box (V5R3). My… >>> More
Google App Engine - Spring Security Issue (java.security.AccessControlException)

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm currently getting the AccessControlException below when I deploy to app engine (I don't see it when I run in my local environment). I'm using GAE 1.3.1, Spring 3.0.1, and Spring Security 3.0.2. Any ideas how to get around this issue? It appears to be an issue with Spring Security trying to get… >>> More