CIS Ubuntu 14.04 LTS - 1.5.1 Ensure core dumps are restricted

DevOps & Security

Verify that core dumps are restricted to prevent information disclosure from memory dumps

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1.5.1 Ensure core dumps are restricted (Scored)

Profile Applicability

Level 1 - Server
Level 1 - Workstation

Description

A core dump is the memory of an executable program. It is generally used to determine why a program aborted. It can also be used to glean confidential information from a core file. The system provides the ability to set a soft limit for core dumps, but this can be overridden by the user.

Rationale

Setting a hard limit on core dumps prevents users from overriding the soft variable. If core dumps are required, consider setting limits for user groups (see limits.conf(5)). In addition, setting the fs.suid_dumpable variable to 0 will prevent setuid programs from dumping core.

Audit Procedure

Run the following commands and verify output matches:

grep "hard core" /etc/security/limits.conf /etc/security/limits.d/*
# Expected: * hard core 0
sysctl fs.suid_dumpable
# Expected: fs.suid_dumpable = 0
grep "fs\.suid_dumpable" /etc/sysctl.conf /etc/sysctl.d/*
# Expected: fs.suid_dumpable = 0

Expected Result

* hard core 0
fs.suid_dumpable = 0
fs.suid_dumpable = 0

Remediation

Add the following line to /etc/security/limits.conf or a /etc/security/limits.d/* file:

* hard core 0

Set the following parameter in /etc/sysctl.conf or a /etc/sysctl.d/* file:

fs.suid_dumpable = 0

Run the following command to set the active kernel parameter:

sysctl -w fs.suid_dumpable=0

Default Value

Not applicable.

Notes

It has been reported that due to Ubuntu bug #50093 this setting (and some others) can fail to apply properly on reboot requiring it to be manually re-applied. One method of accomplishing this is to add sysctl -p to run on reboot to your systems crontab.

References

CIS Controls: 13 Data Protection

Profile

Level 1 - Server
Level 1 - Workstation