Meet MailSniper, a new pen tester tool that may be of interest to you if you need to find sensitive data such as passwords, credit card numbers and healthcare data, or need to access databases, or even to discover insider and network architecture information. Beau Bullockfrom the penetration testing firm Black Hills Information Securitycited a Mandiant M-Trends Report pdf which claimed organizations are compromised an average of days before detecting a breach.

That long of a window gives attackers plenty of time to locate, compromise and exfiltrate sensitive data; pen testers, however, may only have a window of five days or less to do the same thing in order to prove risk to an organization. While Microsoft Exchange does have tools for searching email, Bullock was intent on creating a tool which could provide a new search function capable of searching every mailbox in a domain for specific terms. It becomes a brand new privilege escalation vector. Invoke-GlobalMailSearch searches through all mailboxes on an Exchange server.

Bullock had plenty of other search suggestions which could be used to discover sensitive information, insider intel and network architecture information. He explained:. Having the power to search through email is huge when hunting for sensitive data. MailSniper may prove useful to pen testers needing to quickly find sensitive data on a network as well as escalate privileges.

Bullock suggested that a blue team might use it to discover if employees are blowing off company policy and sending sensitive info in emails. You can grab MailSniper on GitHub. Smith not her real name is a freelance writer and programmer with a special and somewhat personal interest in IT privacy and security issues.

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Meet MailSniper, a tool to search Microsoft Exchange emails for sensitive info

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More from the IDG Network. Top tools for preventing data leaks. Cloud access security brokers deliver must-have protection for your SaaS apps. He explained: Having the power to search through email is huge when hunting for sensitive data. The 10 most powerful cybersecurity companies.MailSniper is a penetration testing tool for searching through email in a Microsoft Exchange environment for specific terms passwords, insider intel, network architecture information, etc.

It can be used as a non-administrative user to search their own. It can be used as a non-administrative user to search their own email, or by an Exchange administrator to search the mailboxes of every user in a domain.

Can Exchange Web Services be Accessed by Bypassing Multi-Factor Authentication?

For more information about MailSniper check out this blog post. For more information about additional MailSniper modules check out this blog post. There are two main functions in MailSniper. After this role has been granted the Invoke-GlobalMailSearch function creates a list of all mailboxes in the Exchange database. It then connects to Exchange Web Services using the impersonation role to gather a number of emails from each mailbox, and ultimately searches through them for specific terms.

It then searches through them for specific terms. If this does not succeed the script will attempt to connect to Exchange Web Services where it will attempt to gather the Global Address List. Invoke-PasswordSprayOWA is a module that will attempt to connect to an Outlook Web Access portal and perform a password spraying attack using a userlist and a single password.

Invoke-PasswordSprayEWS is a module that will attempt to connect to an Exchange Web Services portal and perform a password spraying attack using a userlist and a single password. It can be used as a non-administrative user to search their own Home Repositories MailSniper. MailSniper 0 MailSniper is a penetration testing tool for searching through email in a Microsoft Exchange environment for specific terms passwords, insider intel, network architecture information, etc.

Star Fork Watch Issue Download. MailSniper MailSniper is a penetration testing tool for searching through email in a Microsoft Exchange environment for specific terms passwords, insider intel, network architecture information, etc. AutoDiscoverEmail - A valid email address that will be used to autodiscover where the Exchange server is located.

MailsPerUser - The total number of emails to return for each mailbox. Terms - Certain terms to search through each email subject and body for. ExchangeVersion - Specify the version of Exchange server to connect to.EWS is a web-based API enabled on Exchange servers that Microsoft recommends customers use when developing client applications that need to interface with Exchange.

In this post it was demonstrated that Exchange Web Services is not being protected by a popular two-factor authentication software, and it was possible to still read emails of a user after only obtaining their login credentials. Share this The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US.

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Sensitive Data Discovery in Email with MailSniper - Tradecraft Security Weekly #11

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Necessary Always Enabled.MailSniper requires unfettered access to OWA in order to attack it effectively. Grabbing the GAL can be beneficial in many ways on an engagement since they contain valid usernames. For instance, the names can be used in a password spraying campaign to discover other users using weak passwords, but are also part of a VPN or RDP group. Even though the write-up is specific to KEMP LoadMaster, the same method should apply to other systems that rely on a valid cookie to redirect traffic to the actual server hosting the service.

What all this means is that traffic requesting a particular service OWA in this instance will need to authenticate to the authentication provider prior to hitting the OWA portal. Once authenticated, a cookie is set if using form-based authentication and included in the header of future requests to allow all subsequent traffic access to the real server. KEMP has a nice technical break down of the entire process here.

Capturing the cookie is simple enough to do through Burp, Zap, etc. Once you have valid creds, proxy the authentication request, then take note of the set-cookie in the response:. Make a copy of MailSniper. Do a search for Get-GlobalAddressList and scroll down a bit until you see the try statement.

Save and import the modified MailSniper. When you dump the GAL using the modified script, MailSniper should now use the cookie you captured as part of its request. Just a side note — in most cases, the cookie will expire in a short amount of time. Your email address will not be published. Once you have valid creds, proxy the authentication request, then take note of the set-cookie in the response: Make a copy of MailSniper.

Published in Uncategorized. No Older Posts Return to Blog. Leave a Reply Cancel reply Your email address will not be published.Vulnerability Walkthrough Educationvulnerabilitywalkthrough.

mailsniper owa

From time to time, when we see a particular vulnerability that keeps showing up over and over again during penetration testing engagements, we like to write about it and help spread awareness. This can help explain the issue, the subsequent risk it presents to your organization, and how to successfully remediate the issue or at least mitigate some of the risk.

First, username enumeration is a vulnerability that occurs when an attacker can submit a request to an application, such as a login request, password reset request, or registration request, and the application response will indicate the validity of the username submitted. Either way, an attacker can abuse this to automatically build a list of valid usernames that can be used with password attacks.

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In the case of Microsoft OWA servers, a valid username submitted with a login request has a much faster response time than an invalid username. So however they are able to accomplish it, whether it be an overt enumeration method or a more subtle one like timing, an attacker being able to build a big list of valid usernames is a big risk.

This provides half of what you need to login to whatever application is being targeted, significantly increasing the chances of someone gaining unauthorized access. If you run across a login interface for Microsoft OWA, Microsoft EWS, Microsoft Lync, or any other application you think may be vulnerable to timing-based username enumeration, what do you do next?

Well there are a ton of different tools to help facilitate this attack, but all your really need is your trusty intercepting proxy our default choice is usually Burp Suite Pro. One tool you may want to consider in tandem with your intercepting proxy is MailSniper.

mailsniper owa

This tool, released by Beau Bullock aka dafthack, is really useful for automating portions of the attack and facilitating information gathering post-exploitation. Keep in mind this is an online process with an associated timing delay, so it is not going to be super speedy.

You can usually try somewhere between and usernames an hour, depending on your Internet speeds and the response time of the target. With that in mind, we want to test high probability usernames first. To get these potential usernames, I generally use a two-pronged approach:. So with the names of potential employees, we need to create a single list of potential usernames.

Most companies follow a standard and use something like first.

Outlook Web Access Two-Factor Authentication Bypass Exists

With your intercepting proxy, capture a login request to the OWA server. The POST request shown below is what you should see that you can then send to Intruder in Burp Suite to modify and start the process of validating usernames.

We can then mark the username field in intruder to rotate through our list of potential usernames we created, and analyze the timing of the responses. That module requires the target hostname mail. Your results should look something like this:. And now an attacker has a potentially substantial list of valid usernames that they can use to run password attacks against these exposed login interfaces, conduct social engineering attacks using this information, or attempt to find valid credentials from other sources and use credential stuffing.

So that leaves you with moving away from on-prem email solutions and instead using Office which is not vulnerable to any type of username enumeration or not exposing peripheral applications like Microsoft Lync to the Internet and making sure it is only accessible from the internal network.

Besides truly fixing the root cause, your next best bets are some compensating controls that can help reduce the risk of unauthorized access. The most effective control would be to implement multi-factor authentication MFA on any of your exposed login interfaces. This way, even if an attacker did gain access to valid credentials using the list of enumerated usernames, they would need that second factor to get in. A password policy with a longer minimum length requirement e. Make sure your logging and alerting environment is configured to detect multiple invalid authentication attempts from a single source, regardless of the username to identify spraying activity and brute force attemptsso your admins can stop these attacks in progress.

Our gap analysis is an interview-driven process which comprehensively explores your current security policies, procedures, and techniques. This assessment involves a comprehensive audit on all the ways electronic protected health information ePHI is stored, processed, or transmitted on your network.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again.

If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. MailSniper is a penetration testing tool for searching through email in a Microsoft Exchange environment for specific terms passwords, insider intel, network architecture information, etc. It can be used as a non-administrative user to search their own email, or by an Exchange administrator to search the mailboxes of every user in a domain.

mailsniper owa

For more information about the primary MailSniper functionality check out this blog post. There are two main functions in MailSniper.

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Invoke-GlobalMailSearch is a module that will connect to a Microsoft Exchange server and grant the "ApplicationImpersonation" role to a specified user. Having the "ApplicationImpersonation" role allows that user to search through all other domain user's mailboxes. After this role has been granted the Invoke-GlobalMailSearch function creates a list of all mailboxes in the Exchange database. It then connects to Exchange Web Services using the impersonation role to gather a number of emails from each mailbox, and ultimately searches through them for specific terms.

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This command will connect to the Exchange server located at 'Exch01' and prompt for administrative credentials i. Once administrative credentials have been entered a PS remoting session is setup to the Exchange server where the ApplicationImpersonation role is then granted to the "current-username" user. Invoke-SelfSearch is a module that will connect to a Microsoft Exchange server using Exchange Web Services to gather a number of emails from the current user's mailbox.

It then searches through them for specific terms. This could potentially assist in privilege escalation after obtaining a user's credentials or assist in locating sensitive data as a non-admin. Get-GlobalAddressList is a module that will first attempt to connect to an Outlook Web Access portal and utilize the "FindPeople" method only available in Exchange and up of gathering email addresses from the Global Address List. If this does not succeed the script will attempt to connect to Exchange Web Services where it will attempt to gather the Global Address List.

mailsniper owa

Get-MailboxFolders is a module that will connect to a Microsoft Exchange server using Exchange Web Services to gather a list of folders from the current user's mailbox. Invoke-PasswordSprayOWA is a module that will attempt to connect to an Outlook Web Access portal and perform a password spraying attack using a userlist and a single password.

Invoke-PasswordSprayEWS is a module that will attempt to connect to an Exchange Web Services portal and perform a password spraying attack using a userlist and a single password.

Invoke-DomainHarvestOWA is a module that will attempt to connect to an Outlook Web Access portal and determine a valid domain name for logging into the portal from the WWW-Authenticate header returned in a web response from the server or based off of small timing differences in login attempts. Invoke-UsernameHarvestOWA is a module that will attempt to connect to an Outlook Web Access portal and harvest valid usernames based off of small timing differences in login attempts.

Invoke-OpenInboxFinder is a module that will attempt to determine if the current user running MailSniper has access to the Inbox of each email address in a list of addresses. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.Very often on external penetration tests we perform a reconnaissance phase that might yield us some email addresses or usernames of an organization.

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If we can successfully find valid credentials for any one of them, and the organization has an Outlook Web Access or Exchange Web Services portal it is possible to download the entire Global Address List from the Exchange server.

So, from one valid credential we can now have access to all email addresses for every employee of an organization. There is a function called FindPeople that will allow you to pull back the entire GAL with a single request. Unfortunately, this function is only implemented in Exchange version This method can take a bit longer due to the fact that EWS will only let you search results at a time.

After obtaining the full email list you can then feed that back into password spraying attacks where you will likely gain more valid credentials. Password spraying is an attack where instead of trying to brute force many password attempts for a single user account we try one password across many user accounts. Both of the functions are multi-threaded.

Just pass the -Threads option and specify a number of threads 15 seems to be a pretty good starting point. Spraying that same list of users against EWS took only 9 minutes and 28 seconds. For more information about MailSniper check out this blog post. Email Address. Get-GlobalAddressList Very often on external penetration tests we perform a reconnaissance phase that might yield us some email addresses or usernames of an organization. Join 2, other subscribers Email Address Subscribe.


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