Cis Ubuntu1604 V200 6 2 6

---
name: cis-ubuntu1604-v200-6-2-6
description: "Ensure users' home directories permissions are 750 or more restrictive"
category: cis-iam
version: "2.0.0"
author: cyberstrike-official
tags: [cis, ubuntu, linux, ubuntu-16.04, user-management, maintenance]
cis_id: "6.2.6"
cis_benchmark: "CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0"
tech_stack: [ubuntu, linux]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 6.2.6

## Profile

- **Level:** 1 - Server
- **Level:** 1 - Workstation
- **Assessment Status:** Automated

## Description

While the system administrator can establish secure permissions for users' home directories, the users can easily override these.

## Rationale

Group or world-writable user home directories 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:

```bash
#!/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
    echo "User: \"$user\" home directory: \"$dir\" doesn't exist"
  else
    dirperm=$(stat -L -c "%A" "$dir")
    if [ "$(echo "$dirperm" | cut -c6)" != "-" ] || [ "$(echo "$dirperm" |
cut -c8)" != "-" ] || [ "$(echo "$dirperm" | cut -c9)" != "-" ] || [ "$(echo
"$dirperm" | cut -c10)" != "-" ]; then
      echo "User: \"$user\" home directory: \"$dir\" has permissions:
\"$(stat -L -c "%a" "$dir")\""
    fi
  fi
done
```

## Expected Result

No output should be returned.

## Remediation

### Command Line

Making global modifications to user home directories 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 file permissions and determine the action to be taken in accordance with site policy.

The following script can be used to remove permissions in excess of `750` from users' home directories:

```bash
#!/bin/bash
awk -F: '($1!~/(halt|sync|shutdown)/ && $7!~/^(\/usr)?\/sbin\/nologin(\/)?\$/
&& $7!~/(\/usr)?\/bin\/false(\/)?\$/) {print $6}' /etc/passwd | while read -r
dir; do
  if [ -d "$dir" ]; then
    dirperm=$(stat -L -c "%A" "$dir")
    if [ "$(echo "$dirperm" | cut -c6)" != "-" ] || [ "$(echo "$dirperm" |
cut -c8)" != "-" ] || [ "$(echo "$dirperm" | cut -c9)" != "-" ] || [ "$(echo
"$dirperm" | cut -c10)" != "-" ]; then
      chmod g-w,o-rwx "$dir"
    fi
  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 Lists<br/>Protect 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. |      |      |      |