How Does HSS Block Brute-Force Attacks?

Protection Scope

HSS can block attacks on MySQL, SQL Server 2012, VSFTP, SSH, and RDP.

If MySQL or VSFTP is installed on your server, after HSS is enabled, the agent will add rules to iptables to prevent MySQL and VSFTP brute force attacks. When detecting a brute-force attack, HSS will add the source IP address to the blocking list. The added rules are highlighted below.

Figure 1 Added rules

How Brute-Force Attacks Are Blocked

Brute-force attacks are a type of common intrusion attacks. Attackers submit many server passwords until eventually guessing correctly and gaining control over a server.

HSS uses brute-force detection algorithms and an IP address blacklist to effectively prevent brute-force attacks and block attacking IP addresses. The blocking duration for suspicious SSH attacks is 12 hours and that for other suspicious attacks is 24 hours. If a blocked IP address does not perform brute-force attacks in the default blocking duration, it will be automatically unblocked. HSS supports 2FA to authenticate user identity, effectively blocking account attacks.

You can set common login IP addresses and SSH IP address whitelist that will not be blocked.

If HSS detects account cracking attacks on servers using Kunpeng EulerOS (EulerOS with ARM) or CentOS 8.0 or later, it does not block the source IP addresses and only generates alarms. The SSH login IP address whitelist does not take effect for such servers.

Alarm Policies

• If a hacker successfully cracks the password and logs in to a server, a real-time alarm will be immediately sent to specified recipients.
• If a brute-force attack and risks of account hacking are detected, a real-time alarm will be immediately sent to specified recipients.
• If a brute-force attack is detected and failed, and no unsafe settings (such as weak passwords) are detected on the server, no real-time alarms will be sent. HSS will summarize all attacks in a day in its daily alarm report. You can also view block attacks on the Intrusions page of the HSS console.

Viewing Account Cracking Detection Results

1. Log in to the management console.
2. In the upper left corner of the page, select a region, click , and choose Security & Compliance > Host Security Service.
3. In the table displayed after you click Brute-force attack, you can view blocked attacks on protected servers.
   Figure 2 Brute-force attack
   

4. Click Blocked IP Addresses to check the source IP addresses, attack types, number of intercepted attacks, the time of the first and last interceptions, and the interception status.
   • Blocked indicates the brute-force attack has been blocked by HSS.
   • Canceled indicates you have unblocked the source IP address of the brute force attack.
     

     By default, suspicious SSH attackers are blocked for 12 hours. Other types of suspicious attackers are blocked for 24 hours. If a blocked IP address does not perform brute-force attacks in the default blocking duration, it will be automatically unblocked.

Managing Blocked IP Addresses

• If a server is frequently attacked, you are advised to fix its vulnerabilities in a timely manner and eliminate risks.

  You are advised to enable 2FA, and configure common login IP addresses and the SSH login IP whitelist.

• If a valid IP address is blocked by mistake (for example, after O&M personnel enter incorrect passwords for multiple times), manually unblock the IP address.
  

  If you manually unblocked an IP address, but incorrect password attempts from this IP address reach the threshold again, this IP address will be blocked again.