Other Articles
- Servers – Disable UDF Filesystem
- Servers – Configure /tmp Partition
- Servers – Configure /home Partition
- Servers – Configure /var Partition
- Servers – Configure Shm Partition
- Servers – Enable dm-verity
- Servers – Restrict Core Dump Generation
- Servers – Enable NX Protection
- Servers – Enable Address Space Layout Randomization (ASLR)
- Servers – Configure Message of the Day (MOTD)
- Servers – Configure Local Login Banner
- Servers – Configure Remote Login Banner
- Servers – Configure Message of the Day (MOTD) Permissions
- Servers – Configure Issue Permissions
- Servers – Configure Password Permissions
- Servers – Configure Group Backup Permissions
- Servers – Configure Group Permissions
- Servers – Configure Gshadow Backup Permissions
- Servers – Configure Gshadow Permissions
- Servers – Configure Passwd Backup Permissions
- Servers – Configure Shadow Backup Permissions
- Servers – Configure Shadow Permissions
- Servers – Ensure All Users' Home Directories Exist
- Servers – Ensure No Users Have .forward Files
- Servers – Ensure No Users Have .netrc Files
- Servers – Ensure No Users Have .rhosts Files
- Servers – Ensure Root is the Only UID 0 Account
- Servers – Ensure Root PATH Integrity
- Servers – Remove Legacy '+' Entries from Group
- Servers – Remove Legacy '+' Entries from Passwd
- Servers – Remove Legacy '+' Entries from Shadow
- Servers – Restrict Access to .netrc Files
- Servers – Secure System Accounts
- Servers – Ensure Users' Home Directory Permissions are 750 or More Restrictive
- Servers – Ensure Users Own Their Home Directories
- Servers – Verify Security Of Dot Files
- Servers – Verify Existence of passwd Groups
- Servers – Ensure No Duplicate UIDs Exist
- Servers – Ensure No Duplicate GIDs Exist
- Servers – Ensure No Duplicate User Names Exist
- Servers – Ensure No Duplicate Group Names Exist
- Servers – Ensure Shadow Group Has No Members
- Servers – Ensure Logging is Configured
- Servers – Ensure Journald Compression is Configured
- Servers – Ensure Journald Storage is Configured to Persistent Disk
- Servers – Ensure Permissions on All Logfiles are Configured
- Servers – Verify Time Synchronization with Chrony
- Servers – Ensure Chrony is Configured
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- Servers – Ensure NFS and RPC Services are Disabled
- Servers – Ensure Rsync Service is Disabled
- Servers – Ensure TCP SYN Cookies is Enabled
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- Servers – Ensure IPv6 Loopback Traffic is Configured
- Servers – Ensure IPv6 Outbound and Established Connections are Configured
- Servers – Verify IPv6 Open Ports Rules
- Servers – Ensure Default Deny Firewall Policy is Configured
- Servers – Ensure Loopback Traffic is Configured
- Servers – Ensure Outbound and Established Connections are Configured
- Servers – Ensure Iptables is Installed
- Servers – Ensure Packet Redirect Sending is Disabled
- Servers – Ensure Source Routed Packets are Not Accepted
- Servers – Ensure ICMP Redirects are Not Accepted
- Servers – Ensure Secure ICMP Redirects are Disabled
- Servers – Ensure Suspicious Packets Logging is Enabled
- Servers – Ensure Broadcast ICMP Requests are Ignored
- Servers – Ensure Bogus ICMP Responses are Ignored
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- Servers – Ensure Absence of IPv6 Router Advertisements
- Servers – Ensure SSH SSHD Config Permissions Are Configured
- Servers – Ensure SSH Private Host Key Permissions
- Servers – Ensure SSH Public Host Key Permissions Are Configured
- Servers – Ensure SSH Protocol is Set to 2
- Servers – Ensure SSH LogLevel is Appropriate
- Servers – Ensure SSH X11 Forwarding is Disabled
- Servers – Ensure SSH MaxAuthTries is Set to 4 or Less
- Servers – Ensure SSH IgnoreRhosts is Enabled
- Servers – Ensure SSH HostbasedAuthentication is Disabled
- Servers – Disable SSH Root Login
- Servers – Ensure SSH PermitEmptyPasswords is Disabled
- Servers – Verify SSH Strong Ciphers Strength
- Servers – Verify SSH Strong MAC Algorithms
- Servers – Verify SSH Strong Key Exchange Algorithms
- Servers – Ensure SSH Idle Timeout Interval is Configured
- Servers – Ensure SSH Login Grace Time is Configured
- Servers – Configure SSH Warning Banner
- Servers – Enable SSH PAM Authentication
- Servers – Disable SSH AllowTcpForwarding
- Servers – Configure SSH MaxStartups
- Servers – Verify SSH MaxSessions Configuration
- Servers – Ensure Password Creation Requirements are Configured
- Servers – Ensure Password Reuse is Limited
- Servers – Ensure Password Hashing Algorithm is SHA-512
- Servers – Ensure Password Expiration Days is 365 or Less
- Servers – Ensure Minimum Days Between Password Changes is 7 or More
- Servers – Ensure Password Expiration Warning Days is 7 or More
- Servers – Ensure Inactive Password Lock is 30 Days or Less
- Servers – Ensure All Users Last Password Change Date is in the Past
- Servers – Ensure System Accounts Are Secured
- Servers – Ensure Default Group for Root Account is GID 0
- Servers – Verify Default User Umask
- Servers – Ensure Default User Shell Timeout is 900 Seconds or Less
- Servers – Ensure Root Login is Restricted to System Console
- Servers – Ensure Access to su Command is Restricted
Servers – Enforce Authentication for Single User Mode
Support > Fixing Checks > Server
05 March, 2026
This check ensures that authentication is required before accessing single-user mode (rescue mode).Single-user mode is typically used for system recovery when the system encounters boot issues or when an administrator manually selects it from the bootloader.Requiring authentication helps prevent unauthorized users from gaining root-level access by rebooting the system into rescue mode.
Check Details
- Resource: Server
- Check: Enforce Single User Mode Authentication
- Risk: If authentication is not required in single-user mode, an attacker with physical or console access may reboot the system into rescue mode and gain root privileges without authentication.
Remediation Steps
- Ensure the system is running a Container-Optimized OS image that enforces authentication for single-user (rescue) mode.
- If authentication is not enforced, update the system to a newer Container-Optimized OS image that requires authentication before entering single-user mode.
Note: The Container-Optimized OS root filesystem is read-only. Configuration changes to rescue or emergency service files cannot be permanently modified on the running system. If authentication is not enforced, the system must be updated to an OS image that includes the required configuration.