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The 24-hour Bug in Microsoft Exchange Mailbox Auditing

Mon, 14 Dec 2015 16:36:48 GMT

"This is the official LOGbinder page for tracking the Exchange  24-hour mailbox audit bug. You can keep up with everything my team knows and  is doing by checking this page often.” – Randy Franklin Smith

LOGbinder bulletin, December 14, 2015 -- While investigating a support case, LOGbinder discovered a non-obvious yet critical bug in Exchange audit logging that essentially delays your ability to detect non-owner mailbox access for 24 hours. The PowerShell cmdlets New-MailboxAuditLogSearch and Search-MailboxAuditLog produce audit search results that are unpredictable and inconsistent when auditing all mailboxes and the start date is less than 24 hours ago.

We have notified Microsoft about the problem and they have confirmed it as a bug but have told us that they have no timeline for a bug fix. The bug affects Exchange Server 2010, 2013 and 2016.

What is the risk?

The risk to you is that you may never know you have an Exchange Server data breach – despite performing regular audits.

This strikes to the very core of application security audit. Not only is a 24-hour audit delay 24 hours too long, audit integrity is absolutely critical to security intelligence operations.

Details about the Bug

We encourage you to watch an 8-minute clip of our recent Exchange mailbox audit webinar embedded below. In this clip we discuss specifics about the bug and how it could be affecting you.

Here are the highlights about the bug:

  • The bug returns unpredictable results when auditing all mailboxes: you may get no events at all when there are events, you may get only a few events, or you may get all matching events as you should. 
  • Unless you are looking for specific events repeatedly – or you audit your audit results – you will never notice the problem. 
  • The bug is not documented. We have reported this issue to Microsoft; they have confirmed it is a bug and said they have no solution timeline to share. Microsoft’s suggested workaround is to use a date range greater than 24 hours.

LOGbinder’s View on this Issue

The bug introduces a huge business, compliance and security impact. It is simply unacceptable to be unable to detect or respond to information theft for 24 hours. Security audits need to be available in seconds, not minutes! A delay brings compliance issues and prevents organizations from handling Edward Snowden-like information grabs before the culprit is out of reach.

We believe that you need to get audit results off the system (or application) where they are generated as fast as possible, without causing harm to the application or system while using least privilege.

What LOGbinder is Doing

Our development team is solving the problem. To ensure audit integrity we have released an update to our Exchange audit solution that all customers should download and begin using immediately. LOGbinder for Exchange 3.1 allows customers to choose whether they wish to perform audits in less than 24 hours, but defaults to the delay that we know will provide all the audit results requested. Click here to download: https://www.logbinder.com/Form/LBEXDownload

But LOGbinder for Exchange 3.1 is only the first phase of the ultimate solution. We are working with Microsoft and the Exchange Server community to raise awareness of the issue to get it to the top priority within Microsoft.

Exchange Server’s audit function is quite good. Leaving the bug aside, few applications make such an effort to audit events. Microsoft deserves a lot of credit (more than they usually get) for embedding both an admin and mailbox audit function in the application.

But if and until Microsoft does fix this bug we realize you need to protect your organization and fulfill compliance requirements.

Coming soon: Targeted, Synchronous Mailbox Audit Log Collection

Our new edition of LOGbinder for Exchange due Q1 2016 will continue to maintain audit log integrity using least-privilege and minimal impact, and deliver the admin audit as well as mailbox audit logs with a new robust and stable technology to provide audit logs for high-priority mailboxes in near real-time!

Like our current version, you can specify groups or OUs of executives or other sensitive mailboxes, and LOGbinder will use synchronous mailbox audit log searches on those groups and/or OUs. (To understand why “synchronous” is so significant, watch the full edition of our webinar Detect and monitor threats to your executive mailboxes with Exchange mailbox auditing. Non-targeted mailbox audit logs that should also be monitored for non-owner access will be returned in 24 hours (if and when Microsoft fixes the bug).

The benefit is that your targeted mailboxes will get to your SIEM in minutes if not seconds! Click here to get the beta of the newest edition of LOGbinder for Exchange when it becomes available.

What You Can Do

Stay up-to-date and get the latest innovations from LOGbinder.

If you are already a LOGbinder for Exchange customer, the first thing you should do is download the latest version. This will ensure you get all the audits you should be getting to the SIEM, even if they are delayed 24 hours. Some organizations have reported that they have no issues with the 24-hour delay.

Register for a beta of the coming new edition of LOGbinder for Exchange that will deliver targeted mailbox audit using synchronous search and real-time log delivery.

Open a support case with Microsoft to let them know this bug is a problem for you and send us the case ID. LOGbinder is taking a proactive approach with Microsoft and the Exchange Server community to help solve this problem and your participation will be of great value to the process.

Join the discussion at http://forum.ultimatewindowssecurity.com/Forum1608-1.aspx.

Bookmark this page and check it often to see what news and updates there have been. We will keep you up-to-date with everything we know and are doing by adding news items to the top of the page (content will be in reverse date-order top-to-bottom).

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