Red Hat Enterprise Linux 9 Security Technical Implementation Guide
Rules, Groups, and Values defined within the XCCDF Benchmark
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RHEL 9 must disable the chrony daemon from acting as a server.
<VulnDiscussion>Minimizing the exposure of the server functionality of the chrony daemon diminishes the attack surface. Satisfies: SRG-OS-00...Rule Low Severity -
SRG-OS-000096-GPOS-00050
<GroupDescription></GroupDescription>Group -
RHEL 9 must disable network management of the chrony daemon.
<VulnDiscussion>Not exposing the management interface of the chrony daemon on the network diminishes the attack space. Satisfies: SRG-OS-000...Rule Low Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 systems using Domain Name Servers (DNS) resolution must have at least two name servers configured.
<VulnDiscussion>To provide availability for name resolution services, multiple redundant name servers are mandated. A failure in name resolut...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must configure a DNS processing mode in Network Manager.
<VulnDiscussion>In order to ensure that DNS resolver settings are respected, a DNS mode in Network Manager must be configured.</VulnDiscus...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must forward mail from postmaster to the root account using a postfix alias.
<VulnDiscussion>It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required....Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 libreswan package must be installed.
<VulnDiscussion>Providing the ability for remote users or systems to initiate a secure VPN connection protects information when it is transmi...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
There must be no shosts.equiv files on RHEL 9.
<VulnDiscussion>The shosts.equiv files are used to configure host-based authentication for the system via SSH. Host-based authentication is n...Rule High Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
There must be no .shosts files on RHEL 9.
<VulnDiscussion>The .shosts files are used to configure host-based authentication for individual users or the system via SSH. Host-based auth...Rule High Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must be configured to use TCP syncookies.
<VulnDiscussion>Denial of service (DoS) is a condition when a resource is not available for legitimate users. When this occurs, the organizat...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must ignore Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages.
<VulnDiscussion>ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. Thes...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not forward Internet Protocol version 4 (IPv4) source-routed packets.
<VulnDiscussion>Source-routed packets allow the source of the packet to suggest routers forward the packet along a different path than config...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must log IPv4 packets with impossible addresses.
<VulnDiscussion>The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and re...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must log IPv4 packets with impossible addresses by default.
<VulnDiscussion>The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and re...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must use reverse path filtering on all IPv4 interfaces.
<VulnDiscussion>Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the inte...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must prevent IPv4 Internet Control Message Protocol (ICMP) redirect messages from being accepted.
<VulnDiscussion>ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. Thes...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not forward IPv4 source-routed packets by default.
<VulnDiscussion>Source-routed packets allow the source of the packet to suggest routers forward the packet along a different path than config...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must use a reverse-path filter for IPv4 network traffic when possible by default.
<VulnDiscussion>Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the inte...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.
<VulnDiscussion>Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks. Ignoring ...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must limit the number of bogus Internet Control Message Protocol (ICMP) response errors logs.
<VulnDiscussion>Some routers will send responses to broadcast frames that violate RFC-1122, which fills up a log file system with many useles...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not send Internet Control Message Protocol (ICMP) redirects.
<VulnDiscussion>ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. Thes...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not allow interfaces to perform Internet Control Message Protocol (ICMP) redirects by default.
<VulnDiscussion>ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. Thes...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not enable IPv4 packet forwarding unless the system is a router.
<VulnDiscussion>Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this c...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not accept router advertisements on all IPv6 interfaces.
<VulnDiscussion>An illicit router advertisement message could result in a man-in-the-middle attack.</VulnDiscussion><FalsePositives&...Rule Medium Severity -
RHEL 9 SSHD must not allow blank passwords.
<VulnDiscussion>If an account has an empty password, anyone could log on and run commands with the privileges of that account. Accounts with ...Rule High Severity -
RHEL 9 must not forward IPv6 source-routed packets.
<VulnDiscussion>Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than c...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group -
RHEL 9 must not enable IPv6 packet forwarding unless the system is a router.
<VulnDiscussion>IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets bet...Rule Medium Severity -
SRG-OS-000480-GPOS-00227
<GroupDescription></GroupDescription>Group
Node 2
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