A Pass-the-Hash (PtH) attack is a technique used by attackers to authenticate to a remote server or service using the hashed representation of a password instead of the actual plaintext password. Attackers obtain the NTLM or LANMAN hash of a user's password and use this hash to trick authentication systems. This method is particularly common on Windows systems and is a highly effective lateral movement technique. The attack exploits the authentication protocols of certain systems, primarily those running Windows, which accept password hashes for authentication.
If the user's password is changed, the stolen hash becomes useless. Therefore, best security practices recommend changing passwords at least once every 30 to 90 days.
Attack Flow Diagram:
What are the steps involved in the Pass-the-Hash Attack?
Step 1: Hash Capture
The attacker gains access to an initial system within the target network, typically through phishing, exploiting vulnerabilities, or other attack methods.
Once inside, the attacker retrieves password hashes from the compromised system. This is achieved using tools capable of extracting hashes from memory or the Security Account Manager (SAM) database. Common tools include Mimikatz, fgdump, and pwdump.
Step 2: Use the Captured Hash
The attacker leverages the captured password hash to authenticate to other systems or services within the same network. By submitting the hash to the authentication protocol (such as NTLM), the attacker gains access without needing the actual plaintext password. This allows them to impersonate the user whose hash was stolen.
Step 3: Lateral Movement
With initial access established, the attacker proceeds to move horizontally across the network using the same or additional captured hashes. This lateral movement enables them to escalate privileges, access sensitive information, and compromise additional systems. The exploitation of NTLM hashes for authentication facilitates this widespread access within Windows environments.
How to Detect Pass-the-Hash (PtH) Attacks?
Deploy network-based IDS to identify suspicious activities.
Deploy decoy systems (honeypots) and fake credentials (honeytokens) to detect and alert on unauthorized access attempts by attackers.
Implement machine learning and anomaly detection algorithms.
Through Log Analysis, Regularly analyze authentication logs to spot anomalies.
Utilize EDR solutions to monitor and analyze endpoint activities, looking for signs of credential theft and misuse.
Utilize Security Information and Event Management (SIEM) systems to correlate events across the network.
Track unusual activity like logins from different geographic locations simultaneously or access during unusual hours.
How to Configure Security Policies to Detect Attacks in Your Network?
In conclusion, Pass-the-Hash (PtH) attacks are a major security threat, especially in networks using NTLM and LANMAN protocols. Understanding the attack steps—hash capture, hash authentication, and lateral movement—helps in defense. Effective detection methods like behavioral monitoring, log inspection, and endpoint detection are crucial. Regular password changes and multi-factor authentication further enhance security. Proactive monitoring and robust security policies are essential to mitigate PtH attack risks and protect networks from unauthorized access.
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