SID-History Injection
The Windows security identifier (SID) is a unique value that identifies a user or group account. SIDs are used by Windows security in both security descriptors and access tokens. (Citation: Microsoft SID) An account can hold additional SIDs in the SID-History Active Directory attribute (Citation: Microsoft SID-History Attribute), allowing inter-operable account migration between domains (e.g., all values in SID-History are included in access tokens). Adversaries may use this mechanism for privilege escalation. With Domain Administrator (or equivalent) rights, harvested or well-known SID values (Citation: Microsoft Well Known SIDs Jun 2017) may be inserted into SID-History to enable impersonation of arbitrary users/groups such as Enterprise Administrators. This manipulation may result in elevated access to local resources and/or access to otherwise inaccessible domains via lateral movement techniques such as Remote Services, Windows Admin Shares, or Windows Remote Management.
Mitigations |
|
| Mitigation | Description |
|---|---|
| Active Directory Configuration |
Implement robust Active Directory configurations using group policies to control access and reduce the attack surface. Specific examples include: * Account Configuration: Use provisioned domain accounts rather than local accounts to leverage centralized control and auditing capabilities. * Interactive Logon Restrictions: Enforce group policies that prohibit interactive logons for accounts that should not directly access systems. * Remote Desktop Settings: Limit Remote Desktop logons to authorized accounts to prevent misuse by adversaries. * Dedicated Administrative Accounts: Create specialized domain-wide accounts that are restricted from interactive logons but can perform specific tasks like installations or repository access. * Authentication Silos: Configure Authentication Silos in Active Directory to create access zones with restrictions based on membership in the Protected Users global security group. This setup enhances security by applying additional protections to high-risk accounts, limiting their exposure to potential attacks. |
| SID-History Injection Mitigation |
Clean up SID-History attributes after legitimate account migration is complete.
Consider applying SID Filtering to interforest trusts, such as forest trusts and external trusts, to exclude SID-History from requests to access domain resources. SID Filtering ensures that any authentication requests over a trust only contain SIDs of security principals from the trusted domain (i.e. preventing the trusted domain from claiming a user has membership in groups outside of the domain).
SID Filtering of forest trusts is enabled by default, but may have been disabled in some cases to allow a child domain to transitively access forest trusts. SID Filtering of external trusts is automatically enabled on all created external trusts using Server 2003 or later domain controllers. (Citation: Microsoft Trust Considerations Nov 2014) (Citation: Microsoft SID Filtering Quarantining Jan 2009) However note that SID Filtering is not automatically applied to legacy trusts or may have been deliberately disabled to allow inter-domain access to resources.
SID Filtering can be applied by: (Citation: Microsoft Netdom Trust Sept 2012)
* Disabling SIDHistory on forest trusts using the netdom tool ( |
Detection
Examine data in user’s SID-History attributes using the PowerShell Get-ADUser Cmdlet (Citation: Microsoft Get-ADUser), especially users who have SID-History values from the same domain. (Citation: AdSecurity SID History Sept 2015)
Monitor Account Management events on Domain Controllers for successful and failed changes to SID-History. (Citation: AdSecurity SID History Sept 2015) (Citation: Microsoft DsAddSidHistory)
Monitor Windows API calls to the DsAddSidHistory function. (Citation: Microsoft DsAddSidHistory)
References
- Metcalf, S. (2015, August 7). Kerberos Golden Tickets are Now More Golden. Retrieved December 1, 2017.
- Microsoft. (2012, September 11). Command-Line Reference - Netdom Trust. Retrieved November 30, 2017.
- Microsoft. (n.d.). Configuring SID Filter Quarantining on External Trusts. Retrieved November 30, 2017.
- Microsoft. (2014, November 19). Security Considerations for Trusts. Retrieved November 30, 2017.
- Microsoft. (n.d.). Using DsAddSidHistory. Retrieved November 30, 2017.
- Metcalf, S. (2015, September 19). Sneaky Active Directory Persistence #14: SID History. Retrieved November 30, 2017.
- Microsoft. (n.d.). Active Directory Cmdlets - Get-ADUser. Retrieved November 30, 2017.
- Microsoft. (2017, June 23). Well-known security identifiers in Windows operating systems. Retrieved November 30, 2017.
- Microsoft. (n.d.). Active Directory Schema - SID-History attribute. Retrieved November 30, 2017.
- Microsoft. (n.d.). Security Identifiers. Retrieved November 30, 2017.
Связанные риски
Каталоги
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