👉 Overview
👀 What ?
Windows SID-History Injection is a technique often used by attackers to gain unauthorized access to Windows systems. The Security Identifier (SID) is a unique value that identifies a user or group in Windows. The SID-History attribute of an account in Active Directory holds the SIDs of the account's former security groups, which allows access to resources even after moving the account to a new group. By injecting values into this attribute, attackers can impersonate any user and gain their access rights.
🧐 Why ?
Understanding Windows SID-History Injection is vital due to its prevalent use in sophisticated cyber-attacks. The technique allows attackers to stealthily escalate privileges and gain unauthorized access to resources. This can lead to data breaches, system disruptions, and even full system compromise if not detected and mitigated in time.
⛏️ How ?
To use SID-History Injection, attackers first need to gain initial access to the system, usually through methods like phishing or exploiting vulnerabilities. Once inside, they can use various tools to inject a SID into the SID-History attribute of an account. This allows them to impersonate the user associated with the injected SID and gain their access rights. Defending against this requires a combination of strong access controls, regular system monitoring, and employee awareness training.
⏳ When ?
The concept of SID-History Injection has been known and used by attackers for many years. It's especially common in attacks against large, complex organizations with many users and groups in their Active Directory systems.
⚙️ Technical Explanations
At the technical level, SID-History Injection involves manipulating the SID-History attribute of an Active Directory account. The attribute is stored in the NTDS.dit file on the domain controller. Attackers typically use tools like Mimikatz to inject a SID into the attribute. This involves modifying the file directly, which requires high-level system access. Once the SID is injected, the account inherits the access rights of the injected SID's corresponding user or group. This can be any user or group in the system, allowing the attacker to gain a wide range of access rights. Defending against this technique is challenging due to its stealthy nature and the difficulty of monitoring changes to the NTDS.dit file. However, strategies like limiting system access, using strong authentication methods, regularly monitoring system activity, and training employees to recognize potential threats can help mitigate the risk.