[PATCH] Added more NFS prose.

Willy Santos wsantos at redhat.com
Fri Jul 13 20:48:39 UTC 2012


Signed-off-by: Willy Santos <wsantos at redhat.com>
---
 RHEL6/input/services/nfs.xml |   50 +++++++++++++++++++++++++++++++++++++----
 1 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/RHEL6/input/services/nfs.xml b/RHEL6/input/services/nfs.xml
index 1d20041..7f5e049 100644
--- a/RHEL6/input/services/nfs.xml
+++ b/RHEL6/input/services/nfs.xml
@@ -256,8 +256,8 @@ can leave your NFS configuration more open than intended. Therefore, exercise ca
 the file.
 <br /><br />
 The syntax of each line in <tt>/etc/exports</tt> is
-<pre>/DIR	ipaddr1(opt1,opt2) ipaddr2(opt3)</pre>
-where <tt>/DIR</tt> is a directory or filesystem to export, <tt>ipaddrN</tt> is an IP address, netblock,
+<pre>/DIR	host1(opt1,opt2) host2(opt3)</pre>
+where <tt>/DIR</tt> is a directory or filesystem to export, <tt>hostN</tt> is an IP address, netblock,
 hostname, domain, or netgroup to which to export, and <tt>optN</tt> is an option.
 </description>
 </Group> <!-- configure_exports_restrictively -->
@@ -280,20 +280,60 @@ Authorized hosts can be specified in several different formats:
 </description>
 </Group> <!-- use_acl_enforce_auth_restrictions -->
 
+<Group id="export_filesystems_read_only">
+<title>Export Filesystems Read-Only if Possible</title>
+<description>If a filesystem is being exported so that users can view the files in a convenient
+fashion, but there is no need for users to edit those files, exporting the filesystem read-only
+removes an attack vector against the server. The default filesystem export mode is <tt>ro</tt>,
+so do not specify <tt>rw</tt> without a good reason.
+</description>
+</Group> <!-- export_filesystems_read_only -->
+
+<Group id="specify_anonymous_uid_gid">
+<title>Specify UID and GID for Anonymous Connections</title>
+<description>When an NFS server is configured to deny remote <tt>root</tt> access, a selected UID and GID
+are used to handle requests from the remote <tt>root</tt> user. The UID and GID should be chosen from the
+system to provide the appropriate level of non-privileged access. By default, the NFS server will
+map remote <tt>root</tt> users to the <tt>nobody</tt> local account. Specifying the anonymous UID and GID
+as -1 ensures that the remote <tt>root</tt> user is mapped to a local account which has no permissions on the
+system.
+<br /><br />
+To specify the UID and GID for remote <tt>root</tt> users, edit the <tt>/etc/exports</tt> file and add
+<tt>anonuid=-1</tt> and <tt>anongid=-1</tt> to the options list for each export.
+</description>
+</Group> <!-- specify_anonymous_uid_gid -->
+
 <Rule id="use_root_squashing_all_exports">
 <title>Use Root-Squashing on All Exports</title>
 <description>If a filesystem is exported using root squashing, requests from root on the client
 are considered to be unprivileged (mapped to a user such as nobody). This provides some mild
 protection against remote abuse of an NFS server. Root squashing is enabled by default, and
 should not be disabled.
-
-Ensure that no line in <tt>/etc/exports</tt> contains the option <tt>no_root_squash</tt>
+<br /><br />
+Ensure that no line in <tt>/etc/exports</tt> contains the option <tt>no_root_squash</tt>.
 </description>
-<rationale>If the NFS server allows root access to local file systems from remote hosts, this access could be used to compromise the system.</rationale>
+<rationale>If the NFS server allows root access to local file systems from remote hosts, this
+access could be used to compromise the system.</rationale>
 <ident cce="4544-3" />
 <oval id="TO:DO" />
 </Rule>
 
+<Rule id="restrict_nfs_clients_to_privileged_ports">
+<title>Restrict NFS Clients to Privileged Ports</title>
+<description>By default, Linux’s NFS implementation requires that all client requests be made
+from ports less than 1024. If your organization has control over machines connected to its
+network, and if NFS requests are prohibited at the border firewall, this offers some protection
+against malicious requests from unprivileged users. Therefore, the default should not be changed.
+<br /><br />
+Ensure that no line in <tt>/etc/exports</tt> contains the option <tt>insecure</tt>.
+</description>
+<rationale>Allowing client requests to be made from ports higher than 1024 could allow a unprivileged
+user to initiate an NFS connection. If the unprivileged user account has been compromised, an
+attacker could gain access to data on the NFS server.</rationale>
+<ident cce="4465-1" />
+<oval id="TO:DO" />
+</Rule>
+
 </Group> <!-- nfs_configuring_servers -->
 
 </Group>
-- 
1.7.7.6



More information about the scap-security-guide mailing list