How to remediate – ActiveSync Data Collect

1. Introduction

The ActiveSync Data Collect vulnerability gathers information about iPhones and Android phones connected to a server running Microsoft Exchange. This allows administrators to identify managed devices, but also presents a risk if stale device data remains in the system. Impact on confidentiality is low, integrity is medium (due to potential for misidentification), and availability is low.

2. Technical Explanation

This plugin requests ActiveSync device information from Exchange servers. If a device is found, its details are stored for future requests. The vulnerability lies in the potential for outdated or unsupported devices to be listed as managed, creating an inaccurate inventory. There is no direct exploit path; this is an informational issue requiring administrative action.

• Root cause: Stale ActiveSync device information remains on the server.
• Exploit mechanism: An attacker could potentially use a misidentified device to gain access or disrupt services, though this requires further exploitation of Exchange itself.
• Scope: Microsoft Exchange servers running ActiveSync.

3. Detection and Assessment

You can confirm whether devices are listed by checking the ActiveSync device inventory on your Exchange server. A thorough method involves reviewing the list for stale or unsupported devices.

• Quick checks: Use the Exchange Management Shell to view ActiveSync device information.
• Scanning: Nessus vulnerability ID 3714e1ad can identify this issue.
• Logs and evidence: Review Exchange logs for ActiveSync connection events, looking for devices that are no longer active.

Get-ActiveSyncDevice | Format-Table DeviceID, UserPrincipalName, Status

4. Solution / Remediation Steps

The following steps remove stale or unsupported ActiveSync devices from your Exchange server inventory. Only apply to this vulnerability.

4.1 Preparation

• Ensure you have the necessary permissions to run Exchange PowerShell cmdlets. A roll back plan involves restoring from backup if needed.
• Consider a change window and obtain approval from relevant stakeholders.

4.2 Implementation

1. Step 1: Identify stale devices using the `Get-ActiveSyncDevice` cmdlet, filtering by last sync time or status.
2. Step 2: Remove identified devices using the `Remove-ActiveSyncDevice` cmdlet.

4.3 Config or Code Example

Before

Get-ActiveSyncDevice | Format-Table DeviceID, UserPrincipalName, Status

After

Get-ActiveSyncDevice | Where-Object {$_.LastSyncTime -lt (Get-Date).AddDays(-30)} | Remove-ActiveSyncDevice

4.4 Security Practices Relevant to This Vulnerability

Regular inventory management is key to addressing this issue. Least privilege helps limit the impact of misidentified devices. A patch cadence ensures Exchange servers are up to date with security fixes.

• Practice 1: Regular device inventory review to identify and remove stale entries.
• Practice 2: Implement least privilege principles for user accounts accessing Exchange services.

4.5 Automation (Optional)

A script can automate the removal of devices older than a specified date.

# Script to remove stale ActiveSync devices
$DaysOld = 30
Get-ActiveSyncDevice | Where-Object {$_.LastSyncTime -lt (Get-Date).AddDays(-$DaysOld)} | Remove-ActiveSyncDevice -Confirm:$false

5. Verification / Validation

Verify the fix by re-running the `Get-ActiveSyncDevice` cmdlet and confirming that stale devices have been removed. Perform a smoke test to ensure ActiveSync functionality remains operational.

• Post-fix check: Run `Get-ActiveSyncDevice | Format-Table DeviceID, UserPrincipalName, Status` and verify no devices older than the specified threshold are listed.
• Re-test: Re-run the initial detection method to confirm that stale devices are no longer present.
• Smoke test: Verify a user can successfully sync their email and calendar using ActiveSync.

Get-ActiveSyncDevice | Format-Table DeviceID, UserPrincipalName, Status

6. Preventive Measures and Monitoring

Regularly review your ActiveSync device inventory to prevent stale data from accumulating. Update security baselines to include checks for outdated devices.

• Baselines: Include a check in your security baseline to regularly audit ActiveSync device information.
• Pipelines: Consider adding a scheduled task or script to automate the removal of stale devices.
• Asset and patch process: Review Exchange server configurations on a regular basis as part of your asset management process.

7. Risks, Side Effects, and Roll Back

• Risk or side effect 1: Accidental removal of active devices leading to temporary sync issues.
• Roll back: Restore the Exchange database from a recent backup if necessary. Alternatively, manually re-add any incorrectly removed devices using `New-ActiveSyncDevice`.

8. References and Resources

• Vendor advisory or bulletin: http://www.nessus.org/u?3714e1ad