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Introduction:
In the modern cybersecurity landscape, the most devastating breaches often don’t result from sophisticated zero-day exploits, but from a much simpler failure: excessive permissions. Over time, as businesses scale and automation increases, user accounts and service principals accumulate privileges far beyond what is necessary for their function. This “permission creep” creates a dangerous attack surface where adversaries no longer need to “break in”—they simply log in to an account that already has the keys to the kingdom. For Managed Service Providers (MSPs) and internal IT teams, understanding and mitigating this principle of least privilege is the highest-leverage security move available.
Learning Objectives:
- Understand the concept of “permission creep” and why over-provisioned identities are a primary vector for modern cyberattacks.
- Learn how to audit existing permissions across Microsoft 365, Google Workspace, and cloud infrastructures.
- Master the practical steps to implement the principle of least privilege using native tools and commands.
- Identify the difference between “who has access” and “who should have access” to critical data.
You Should Know:
- The Anatomy of Permission Creep: How Access Expands Silently
The core problem, as highlighted in the discourse around MSP security, is that permissions are rarely static. When an employee is hired, they are often granted broad access “just to be safe.” When an application integration is set up (like a CRM syncing with email), it is frequently given full mailbox access rather than specific, scoped permissions. Automation scripts are often run with admin rights because it was easier to code at the time.
This creates a scenario where the “blast radius” of a single compromised credential expands exponentially. An attacker who compromises a low-level marketing assistant’s account might find that, due to an old project, that account still has write access to a finance SharePoint site. The goal of auditing is to revert this expansion.
- Auditing Active Directory and Microsoft 365 with PowerShell
For MSPs managing Windows environments, auditing permissions starts with identifying privileged users. You cannot remove excessive permissions if you don’t know who has them. The following PowerShell commands (run as Global Admin in the Microsoft Graph PowerShell SDK or Exchange Online module) are essential for visibility.
Step 1: Identify All Users with Admin Roles
Open PowerShell as an Administrator and connect to Exchange Online:
Connect-ExchangeOnline
Then, retrieve a list of all users in highly privileged roles. This shows you exactly who has the ability to change settings or access other mailboxes:
Get-RoleGroupMember "Organization Management" | Format-Table Name, RoleGroup
Step 2: Find Inactive but Privileged Users
Often, terminated employees or contractors still have active accounts with permissions. Find users who haven’t logged in for 90 days but still hold admin roles:
Search-AuditLog -StartDate (Get-Date).AddDays(-90) -EndDate (Get-Date) -UserIds "[email protected]" -Operations UserLoggedIn
(Note: Replace `[email protected]` with the user you are auditing). If the log comes back empty, that account is a dormant liability.
3. Mapping the “Blast Radius” in Linux/Unix Environments
In Linux, over-permissioned identities often manifest in `sudoers` file misconfigurations or world-writable files owned by root. Attackers look for accounts that can execute commands as other users without a password.
Step 1: Identify Sudo Privileges
To see what a specific user can do (this is the command an auditor would run, or you would run to verify your own risk):
sudo -l -U username
If this returns (ALL : ALL) ALL, that user has root access—a massive blast radius. If it returns (ALL) NOPASSWD: /bin/systemctl restart service, that user can restart services without a password, which could be abused to restart security tools or launch malicious services.
Step 2: Find Files with Sticky Bit Risks
Search for files with SUID/SGID bits set that are executable by normal users. These are common escalation paths.
find / -perm -4000 -type f 2>/dev/null
This lists files that run with the owner’s permissions (often root) when executed by anyone. If a non-standard binary appears here, it’s a red flag.
4. Cloud Hardening: Auditing IAM Policies (AWS/Azure)
In the cloud, over-permissioned identities are the number one cause of data leaks. The concept of “Automation getting granted broader control” is critical here.
Step 1: Using the AWS IAM Access Analyzer
AWS provides a tool to identify resources shared with an external entity.
aws accessanalyzer list-analyzers aws accessanalyzer list-findings --analyzer-arn <your-analyzer-arn>
This will show you if an S3 bucket policy or IAM role trusts an external account, effectively “giving keys” to someone outside your organization.
Step 2: Azure AD – Reviewing API Permissions
For application registrations in Azure, use the Microsoft Graph API or Azure CLI to check for excessive Application permissions (app roles) versus Delegated permissions (user roles). An app with `Mail.ReadWrite` (Application) can read everyone’s mail in the tenant, not just the signed-in user’s.
Get-AzureADServiceAppRoleAssignment -ObjectId <ObjectId_of_ServicePrincipal>
This command reveals which users/groups are assigned to which app roles, helping you identify if a marketing automation tool has accidentally been granted global reader or worse, mail read access.
5. The Remediation Playbook: Enforcing Least Privilege
Once you have identified the bloat, you must trim it.
For Windows File Servers:
Remove inherited permissions and apply explicit ones. Using `icacls` to reset a folder:
icacls "C:\SharedData" /reset /t /c icacls "C:\SharedData" /grant "Domain Users:(OI)(CI)(RX)" /t icacls "C:\SharedData" /inheritance:r
This breaks inheritance (stopping permission creep from the parent folder), grants read-only access to all domain users, and purges old, excessive ACEs (Access Control Entries).
For Microsoft 365:
Remove a user from a high-privilege role using PowerShell:
Remove-RoleGroupMember -Identity "Organization Management" -Member "[email protected]"
Alternatively, use Privileged Identity Management (PIM) in Azure AD to make roles “just-in-time” rather than permanent.
6. API Security: Securing the Automation Pipeline
APIs are the backbone of modern automation, but they hold keys. An API key with “write” scope for a repository or a database is a prime target.
Step 1: Audit API Tokens in Git
Attackers scrape GitHub for hardcoded secrets. Use `truffleHog` or `git-secrets` to find tokens in your codebase.
trufflehog --regex --entropy=False https://github.com/yourorg/yourrepo.git
This searches for high-entropy strings (potential keys) and regex matches for known service providers.
Step 2: Rotate and Restrict
If a key is found, immediately revoke it. Ensure new keys have the minimal scopes necessary. If an API only needs to read calendar data, it does not need permission to delete emails.
What Undercode Say:
- The Illusion of Complexity: We often search for complex malware, but the reality is that “living off the land” by using existing permissions is quieter and just as destructive. Auditing is not a one-time task but a continuous cycle of verification.
- Automation is a Double-Edged Sword: While automation increases efficiency, automated accounts are often the most privileged and the least monitored. Treat service accounts and application registrations with the same rigor as human user accounts.
- Baseline, Don’t Guess: You cannot secure what you do not measure. Running the commands listed above provides a concrete baseline. Any deviation from this baseline in the future is either a business requirement (which must be documented) or a security incident.
Prediction:
The next major wave of cyber insurance requirements will mandate strict Identity and Access Management (IAM) hygiene. Insurers will soon require policyholders to provide proof of automated permission reviews (like the PowerShell scripts above) and enforce Just-In-Time (JIT) access for all administrative roles. Organizations that fail to move away from permanent, standing privileges will find themselves either uninsurable or facing massive premium hikes, as the market finally prices in the risk of “accounts with keys.” The role of the MSP will shift from tool vendor to compliance verifier, using these exact techniques to validate their clients’ security posture against insurer demands.
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