Microsoft Active Directory Federated Services (ADFS) User Enumeration

Microsoft Active Directory Federated Services (ADFS) suffers from a time-based user enumeration vulnerability.

MD5 | 3c4bec5bac1f0d1cdaef48fbaafa3459

[+] Credits: Joshua Platz aka Binary1985
[+] CVE ID: Requested
[+] Website:

[+] Source:


Active Directory Federated Services (ADFS)

Active Directory Federation Services, a software component developed by Microsoft, can run on Windows Server operating
systems to provide users with single sign-on access to systems and applications located across organizational boundaries.

Vulnerability Type:
Time Based User Enumeration

Vulnerability Details:

ADFS has an excessively long timeout on authentication requests using the correct domain, but invalid user. This is likely
due to the time it takes to search the entire AD directory and return a response. Response times vary with use cases seeing
valid accounts taking only .2 seconds, up to 3 seconds to return an invalid login. However invalid accounts have been seen
to take 15 seconds to respond.

1) Observe the ADFS URL

2) Observe the length of time for an invalid account to return on login attempt (ex 15 seconds) *you must use the valid

3) Observe the length of time for a valid account to return on login attempt (ex 2 seconds) *try domain\administrator or

4) Intercept a request using anything as a valid username and password. Extract the cookie.

5) Add the cookie value to this PoC on line 15.

6) Update the timings within the script to match your tests in step 2 and 3, the goal is to set the command timeout on
line 15 to something slightly greater then the timeout observed in step 3, and then update the logic on line 17
to something reasonable. Remember invalid accounts take a long time, valid accounts are quick

7) Execute the script, providing the ADFS URL as well as the domain and a user list.

Remediation Details:

2018-09-03 - Issue Identified
2018-09-07 - Vendor Notified
2018-09-10 - Vendor Acknowledged Reciept
2018-09-12 - Vendor Indicates Vulnerability does not meet bar for security servicing
2018-10-22 - Public Disclsoure and CVE request through MITRE

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prohibits any malicious use of security related information
or exploits by the author or elsewhere.


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