Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Comments
Deactivated User Accounts Die Hard
Newest First  |  Oldest First  |  Threaded View
mboller
50%
50%
mboller,
User Rank: Apprentice
5/8/2014 | 3:32:15 PM
Re: malicious insider
The user credentials doesn't help. They have to be logged-in already and use the associated TGT. Say the account is disabled while the user is still logged in, that user would have the remaining lifetime of the TGT to wreak havoc. However a password protected screen-saver that has kicked in is enough to stop this attack for a normal user not able to extract the TGT (and if you have that level of access why bother?).

A semi-decent off-boarding process will help mitigate this as well.

For an adversary or pen-tester it wouldn't be the best loot because of its characteristics.

Other issues keep me awake at night, not this :) but an interesting study,
theb0x
100%
0%
theb0x,
User Rank: Ninja
5/7/2014 | 4:34:34 PM
Re: clarification
This can be accomplished by Kerberos GPO. Modify the value "Maximum lifetime for user ticket" and "Maximum lifetime for service ticket".

Both have a default value of 10 hours.

You could also interupt all active OWA sessions with iisreset. Keep in mind this will kill everyones session to webmail, sharepoint, and any outlook client configured as HTTPS/RPC.
Robert McDougal
50%
50%
Robert McDougal,
User Rank: Ninja
5/7/2014 | 3:21:21 PM
Re: Disabled users.
You are exactly correct!  It is best practice to move users to a disabled OU, however, many IT shops do not follow best practices.  I have seen shops that did not even disable their old users.  These shops had accounts which had not logged in over 2 years that were still active.
theb0x
50%
50%
theb0x,
User Rank: Ninja
5/7/2014 | 2:44:00 PM
Disabled users.
I always thought is was common practice in AD to have a Disabled Users OU.
SgS125
50%
50%
SgS125,
User Rank: Ninja
5/7/2014 | 1:57:52 PM
clarification
" and terminating any disable user account requests to access a network resource."

 

Most likely you would want to terminate any disabled user account requests, rather than stop disabling user accounts.  Most SIEM products will allow you to see into whatever detail you wish.  It just requires you to setup the appropriate filters and alerts.

This particular issue would be nice to have a pre built filter for since we know that it exists and can be a problem for us.

Isn't there a way to force the tokens to expire?
Kelly Jackson Higgins
50%
50%
Kelly Jackson Higgins,
User Rank: Strategist
5/7/2014 | 12:40:48 PM
Re: malicious insider
I suppose if an advanced attacker was already inside and able to monitor some of this, they could take advantage as well. But that one seems to pose a lot more work than most attackers are willing to take on.
Randy Naramore
50%
50%
Randy Naramore,
User Rank: Ninja
5/7/2014 | 12:38:51 PM
Re: malicious insider
I agree with you Kelly, insiders would be the only ones to be able to benefit from old or disabled accounts. 
Kelly Jackson Higgins
50%
50%
Kelly Jackson Higgins,
User Rank: Strategist
5/7/2014 | 11:37:19 AM
malicious insider
I would think the insider threat is the biggest risk here--someone gets fired, and tries (successfully) their user credentials in order to take proprietary company information, or just to wreak havoc in some way.


News
FluBot Malware's Rapid Spread May Soon Hit US Phones
Kelly Sheridan, Staff Editor, Dark Reading,  4/28/2021
Slideshows
7 Modern-Day Cybersecurity Realities
Steve Zurier, Contributing Writer,  4/30/2021
Commentary
How to Secure Employees' Home Wi-Fi Networks
Bert Kashyap, CEO and Co-Founder at SecureW2,  4/28/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-31755
PUBLISHED: 2021-05-07
An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /goform/setmac allows attackers to execute arbitrary code on the system via a crafted post request.
CVE-2021-31756
PUBLISHED: 2021-05-07
An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /gofrom/setwanType allows attackers to execute arbitrary code on the system via a crafted post request. This occurs when input vector controlled by malicious attack get copie...
CVE-2021-31757
PUBLISHED: 2021-05-07
An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /goform/setVLAN allows attackers to execute arbitrary code on the system via a crafted post request.
CVE-2021-31758
PUBLISHED: 2021-05-07
An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /goform/setportList allows attackers to execute arbitrary code on the system via a crafted post request.
CVE-2021-31458
PUBLISHED: 2021-05-07
This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit Reader 10.1.1.37576. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handlin...