cyberstrikeus CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 6.2.7
Profile
- Level: 1 - Server
- Level: 1 - Workstation
- Assessment Status: Automated
Description
While the system administrator can establish secure permissions for users' "dot" files, the users can easily override these.
Rationale
Group or world-writable user configuration files may enable malicious users to steal or modify other users' data or to gain another user's system privileges.
Audit Procedure
Command Line
Run the following script and verify no results are returned:
#!/bin/bash
awk -F: '($1!~/(halt|sync|shutdown)/ && $7!~/^(\/usr)?\/sbin\/nologin(\/)?\$/
&& $7!~/(\/usr)?\/bin\/false(\/)?\$/) { print $1 " " $6 }' /etc/passwd | while
read -r user dir; do
if [ -d "$dir" ]; then
for file in "$dir"/.*; do
if [ ! -h "$file" ] && [ -f "$file" ]; then
fileperm=$(stat -L -c "%A" "$file")
if [ "$(echo "$fileperm" | cut -c6)" != "-" ] || [ "$(echo
"$fileperm" | cut -c9)" != "-" ]; then
echo "User: \"$user\" file: \"$file\" has permissions:
\"$fileperm\""
fi
fi
done
fi
done
Expected Result
No output should be returned.
Remediation
Command Line
Making global modifications to users' files without alerting the user community can result in unexpected outages and unhappy users. Therefore, it is recommended that a monitoring policy be established to report user dot file permissions and determine the action to be taken in accordance with site policy.
The following script will remove excessive permissions on dot files within interactive users' home directories.
#!/bin/bash
awk -F: '($1!~/(halt|sync|shutdown)/ && $7!~/^(\/usr)?\/sbin\/nologin(\/)?\$/
&& $7!~/(\/usr)?\/bin\/false(\/)?\$/) { print $1 " " $6 }' | while read -r
user dir; do
if [ -d "$dir" ]; then
for file in "$dir"/.*; do
if [ ! -h "$file" ] && [ -f "$file" ]; then
fileperm=$(stat -L -c "%A" "$file")
if [ "$(echo "$fileperm" | cut -c6)" != "-" ] || [ "$(echo
"$fileperm" | cut -c9)" != "-" ]; then
chmod go-w "$file"
fi
fi
done
fi
done
Default Value
N/A
References
N/A
CIS Controls
| Controls Version | Control | IG 1 | IG 2 | IG 3 |
|---|---|---|---|---|
| v7 | 14.6 Protect Information through Access Control ListsProtect all information stored on systems with file system, network share, claims, application, or database specific access control lists. These controls will enforce the principle that only authorized individuals should have access to the information based on their need to access the information as a part of their responsibilities. |