What is the Windows Security Account Manager (SAM)?

For the average user, logging into a Microsoft Windows system involves entering a username and password. Yet, in the realm of cybersecurity, this seemingly simple process is a meticulously orchestrated mechanism. The linchpin of this process, and a prime target for cyber threats, is the Security Account Manager (SAM).

The SAM is a vital Windows database that securely houses user account credentials, encompassing usernames and hashed passwords. Managed by the Local Security Authority (LSA), it verifies user logins by cross-referencing passwords stored within the SAM database. Located in the c:\windows\system32\config\SAM directory and HKEY_LOCAL_MACHINE\SAM registry, the SAM file is safeguarded during system runtime, preventing direct copying or relocation through exclusive file system locks imposed by the operating system.

While these locks deter online copying, the SAM file’s contents may still be extracted for offline brute-force attacks. Windows employs cryptographic representations, LM and NTLM hashes, to secure passwords:

• LM hash: Originating from the 1980s, LM hashes are the oldest form of password storage in Windows. Vulnerable to password-cracking attacks due to their limited character set, LM hashes can be obtained from the SAM database. LM hash storage can be prevented by using longer passwords or specific Unicode characters.
• NTLM hash: Representing a more secure method of password storage, NTLM hashes are computed based on the entirety of the user-entered password.

SAM Database Attacks:

1. Pass-the-hash attack: Threat actors retrieve stored hashes from the SAM database, using them to gain unauthorized access to network resources by injecting them into local sessions.
2. Corrupting the SAM database: With administrative access, attackers may manipulate the SAM database, creating new accounts, altering passwords, or disabling existing ones.
3. Deleting the SAM database: Although mitigated in Windows XP, prior versions were vulnerable to threat actors bypassing local authentication by deleting the SAM file. Certain methods can still delete the SAM file, necessitating ongoing vigilance.

Best Practices for SAM Database Security:

1. Audit SAM database access: Activate the Audit Policy: Object Access: SAM feature to monitor unauthorized attempts to access the SAM database.
2. Restrict administrative privileges: Minimize users with administrative rights to mitigate privilege escalation threats and limit SAM database access.
3. Implement strong, unique passwords: Utilize robust passwords for each user account to deter pass-the-hash attacks and credential theft methods.
4. Monitor security logs: Analyze security logs for SAM database access, security-related events, and suspicious activity. Establish a response plan for detected incidents.
5. Review accounts regularly: Validate all accounts on the system, removing unnecessary or outdated ones to reduce the attack surface.
6. Enforce access control: Apply measures to safeguard sensitive files and folders, preventing unauthorized entry and enhancing defenses against privilege escalation attacks.

Conclusion:

The Windows SAM holds the key to user credentials and password hashes, making it a prime focus for cyber threats. While NTLM hashes offer improved security, potential risks persist, underscoring the need for organizations to prioritize and implement essential security measures to safeguard Windows credentials.