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.

Security Management //

Access Management

12/15/2017
10:05 AM
Simon Marshall
Simon Marshall
Simon Marshall
50%
50%

Office 365 Flaw Could Lead to 'Stealthy Admin' Headaches

A recently discovered flaw in Microsoft's Office 365 suite could meant that a business's so-called "stealthy admins" could compromise security without even realizing it.

How many "stealthy admins" does your company have? That is, how many users do you have on a domain discretionary access control list (DACL), who have unnecessarily elevated domain privileges?

A major flaw with Microsoft Corp. (Nasdaq: MSFT) Office365 has just been discovered that allows so-called stealthy admins to directly or indirectly pose a threat to enterprise security. The weak point is with Microsoft Azure AD Connector, which allows unwanted stealthy admins to populate during a default installation of Office365, or where users synchronize on-premises Active Directories with those in the cloud.

Hundreds of thousands of enterprises could be affected; any enterprise which has Microsoft Office 365 deployments including an on-premises Active Directory, will have used the Azure AD Connector. The danger is that many organizations are unaware of stealthy admins, and yet their privileges can knowingly or unknowingly be used to cause harm.

(Source: Microsoft)
(Source: Microsoft)

"[Companies] are exposed if there is a rogue internal employee who can reset passwords or if the network has been breached and the attacker has access to credentials of one of the users who can reset passwords," Ajit Sancheti, co-founder and CEO of Preempt, told SecurityNow.

Microsoft has published a security advisory on the vulnerability, which could theoretically offer-up admin permissions for hackers to exfiltrate data or gain operational control over networks. Or perhaps worse, sit there undetected and persistently look very closely at almost everything that's going on in the enterprise.

"We found this vulnerability while we were installing the Preempt product with customers," said Sancheti. "[We] have the ability to detect stealthy admins and we noticed that there was an account that kept showing up in all of our installs. And that account was causing many other stealthy admins to appear."

This vulnerability presents several big risks.

Firstly, stealthy admins can be overlooked because they exist outside of regular security workflows, and that allows malicious members of staff to act as security insiders.

Secondly, stealthy admins can become a prime target for credential theft from outside the organization -- particularly a problem where users are given permissions in error, lack visibility and protection, and are therefore not aware of a credential asset being compromised.

Where do stealthy admins come from? Counterintuitively, they stem from the conservative security principle that enterprises are best served by allowing only enough privilege for a particular person -- or entity -- to get a task done.

Preempt CEO Ajit Sancheti\r\n(Source: Preempt)\r\n
Preempt CEO Ajit Sancheti
\r\n(Source: Preempt)\r\n

Inevitably, higher privileges are required by the few who run the network. In Microsoft Active Directory, these are the domain admins, and their privileges are granted by being a member of a pre-defined security group, such as account operators, administrators or backup operators.

The Microsoft permissions model managed through DACLs can be very complex because multiple rules apply concerning nesting hierarchies, ownership, custom object permissions and other aspects. The net effect is that, according to security advisory from Preempt, "users can achieve effective domain admin permissions even though they are not a member of any of the protected security groups."

Most of the time, stealthy admins are inadvertently created as part of a software package installation or from a business requirement where an administrator follows least privilege guidelines but may forget to follow up and remove them.

There are loopholes, too, where users can elevate themselves to the equivalent of domain admin status. Examples include where a user can be granted permission to change another user's password, or a user can be given permissions to add users to a protected Domain Admins group.

Also, a user can be permitted to replicate the domain, where the permission includes the right to read all password hashes from the domain controller -- once the admin's password hash is acquired, it can be used to perform admin actions.

"It is important to apply the [Microsoft] fix, because otherwise the attack surface is from our experience dramatically increased," said Sancheti.

Related posts:

— Simon Marshall, Technology Journalist, special to Security Now

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Edge-DRsplash-10-edge-articles
I Smell a RAT! New Cybersecurity Threats for the Crypto Industry
David Trepp, Partner, IT Assurance with accounting and advisory firm BPM LLP,  7/9/2021
News
Attacks on Kaseya Servers Led to Ransomware in Less Than 2 Hours
Robert Lemos, Contributing Writer,  7/7/2021
Commentary
It's in the Game (but It Shouldn't Be)
Tal Memran, Cybersecurity Expert, CYE,  7/9/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
How Data Breaches Affect the Enterprise
Data breaches continue to cause negative outcomes for companies worldwide. However, many organizations report that major impacts have declined significantly compared with a year ago, suggesting that many have gotten better at containing breach fallout. Download Dark Reading's Report "How Data Breaches Affect the Enterprise" to delve more into this timely topic.
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-3769
PUBLISHED: 2021-11-30
# Vulnerability in `pygmalion`, `pygmalion-virtualenv` and `refined` themes **Description**: these themes use `print -P` on user-supplied strings to print them to the terminal. All of them do that on git information, particularly the branch name, so if the branch has a specially-crafted name the vul...
CVE-2021-3725
PUBLISHED: 2021-11-30
Vulnerability in dirhistory plugin Description: the widgets that go back and forward in the directory history, triggered by pressing Alt-Left and Alt-Right, use functions that unsafely execute eval on directory names. If you cd into a directory with a carefully-crafted name, then press Alt-Left, the...
CVE-2021-3726
PUBLISHED: 2021-11-30
# Vulnerability in `title` function **Description**: the `title` function defined in `lib/termsupport.zsh` uses `print` to set the terminal title to a user-supplied string. In Oh My Zsh, this function is always used securely, but custom user code could use the `title` function in a way that is unsaf...
CVE-2021-3727
PUBLISHED: 2021-11-30
# Vulnerability in `rand-quote` and `hitokoto` plugins **Description**: the `rand-quote` and `hitokoto` fetch quotes from quotationspage.com and hitokoto.cn respectively, do some process on them and then use `print -P` to print them. If these quotes contained the proper symbols, they could trigger c...
CVE-2021-43790
PUBLISHED: 2021-11-30
Lucet is a native WebAssembly compiler and runtime. There is a bug in the main branch of `lucet-runtime` affecting all versions published to crates.io that allows a use-after-free in an Instance object that could result in memory corruption, data race, or other related issues. This bug was introduce...