T1187: Forced Authentication
Adversaries may gather credential material by invoking or forcing a user to automatically provide authentication information through a mechanism in which they can intercept.
The Server Message Block (SMB) protocol is commonly used in Windows networks for authentication and communication between systems for access to resources and file sharing. When a Windows system attempts to connect to an SMB resource it will automatically attempt to authenticate and send credential information for the current user to the remote system. This behavior is typical in enterprise environments so that users do not need to enter credentials to access network resources.
Web Distributed Authoring and Versioning (WebDAV) is also typically used by Windows systems as a backup protocol when SMB is blocked or fails. WebDAV is an extension of HTTP and will typically operate over TCP ports 80 and 443.
Adversaries may take advantage of this behavior to gain access to user account hashes through forced SMB/WebDAV authentication. An adversary can send an attachment to a user through spearphishing that contains a resource link to an external server controlled by the adversary (i.e. Template Injection), or place a specially crafted file on navigation path for privileged accounts (e.g. .SCF file placed on desktop) or on a publicly accessible share to be accessed by victim(s). When the user's system accesses the untrusted resource, it will attempt authentication and send information, including the user's hashed credentials, over SMB to the adversary-controlled server. With access to the credential hash, an adversary can perform off-line Brute Force cracking to gain access to plaintext credentials.
There are several different ways this can occur. Some specifics from in-the-wild use include:
* A spearphishing attachment containing a document with a resource that is automatically loaded when the document is opened (i.e. Template Injection). The document can include, for example, a request similar to <code>file[:]//[remote address]/Normal.dotm</code> to trigger the SMB request. * A modified .LNK or .SCF file with the icon filename pointing to an external reference such as <code>\\[remote address]\pic.png</code> that will force the system to load the resource when the icon is rendered to repeatedly gather credentials.
Alternatively, by leveraging the <code>EfsRpcOpenFileRaw</code> function, an adversary can send SMB requests to a remote system's MS-EFSRPC interface and force the victim computer to initiate an authentication procedure and share its authentication details. The Encrypting File System Remote Protocol (EFSRPC) is a protocol used in Windows networks for maintenance and management operations on encrypted data that is stored remotely to be accessed over a network. Utilization of <code>EfsRpcOpenFileRaw</code> function in EFSRPC is used to open an encrypted object on the server for backup or restore. Adversaries can collect this data and abuse it as part of a NTLM relay attack to gain access to remote systems on the same internal network.
How it's found
Detect Forced SMB/WebDAV Authentication via lure files and outbound NTLM: Adversary stages a lure that references a remote resource (e.g., LNK/SCF/Office template). When the user opens/renders the file or a shell enumerates icons, the host automatically attempts SMB or WebDAV authentication to the attacker host. The chain is: (1) lure file is created or modified in a user-exposed location → (2) user or system accesses the lure → (3) host makes outbound NTLM (SMB 139/445 or WebDAV over 80/443) to an untrusted destination → (4) repeated attempts from multiple users/hosts or from privileged workstations.
Standards mapping
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is T1187 Forced Authentication?
Adversaries may gather credential material by invoking or forcing a user to automatically provide authentication information through a mechanism in which they can intercept. The Server Message Block (SMB) protocol is commonly used in Windows networks for authentication and communication between systems for access to resources and file sharing. When a Windows system attempts to connect to an SMB resource it will automatically attempt to authenticate and send credential information for the current user to the remote system. This behavior is typical in enterprise environments so that users do not need to enter credentials to access network resources. Web Distributed Authoring and Versioning (WebDAV) is also typically used by Windows systems as a backup protocol when SMB is blocked or fails. WebDAV is an extension of HTTP and will typically operate over TCP ports 80 and 443. Adversaries may take advantage of this behavior to gain access to user account hashes through forced SMB/WebDAV authentication. An adversary can send an attachment to a user through spearphishing that contains a resource link to an external server controlled by the adversary (i.e. Template Injection), or place a specially crafted file on navigation path for privileged accounts (e.g. .SCF file placed on desktop) or on a publicly accessible share to be accessed by victim(s). When the user's system accesses the untrusted resource, it will attempt authentication and send information, including the user's hashed credentials, over SMB to the adversary-controlled server. With access to the credential hash, an adversary can perform off-line Brute Force cracking to gain access to plaintext credentials. There are several different ways this can occur. Some specifics from in-the-wild use include: * A spearphishing attachment containing a document with a resource that is automatically loaded when the document is opened (i.e. Template Injection). The document can include, for example, a request similar to <code>file[:]//[remote address]/Normal.dotm</code> to trigger the SMB request. * A modified .LNK or .SCF file with the icon filename pointing to an external reference such as <code>\\[remote address]\pic.png</code> that will force the system to load the resource when the icon is rendered to repeatedly gather credentials. Alternatively, by leveraging the <code>EfsRpcOpenFileRaw</code> function, an adversary can send SMB requests to a remote system's MS-EFSRPC interface and force the victim computer to initiate an authentication procedure and share its authentication details. The Encrypting File System Remote Protocol (EFSRPC) is a protocol used in Windows networks for maintenance and management operations on encrypted data that is stored remotely to be accessed over a network. Utilization of <code>EfsRpcOpenFileRaw</code> function in EFSRPC is used to open an encrypted object on the server for backup or restore. Adversaries can collect this data and abuse it as part of a NTLM relay attack to gain access to remote systems on the same internal network.
Which tactics does T1187 belong to?
T1187 maps to the Credential Access tactic.
Does TurboPentest test for Forced Authentication?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Related MITRE ATT&CK techniques
- Credential AccessT1003: OS Credential Dumping
- Credential Access, DiscoveryT1040: Network Sniffing
- Credential Access, CollectionT1056: Input Capture
- Credential AccessT1110: Brute Force
- Credential AccessT1111: Multi-Factor Authentication Interception
- Credential AccessT1212: Exploitation for Credential Access
About this reference
These security references are maintained by IntegSec, an offensive-security firm whose team holds CISSP, OSCP, and OSCE certifications and has run thousands of penetration tests. Content is kept current as tools, standards, and attack techniques evolve.
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