4.7.4.1 Ensure sendmail version information is hidden

Information

The recommendation is to change both the default sendmail greeting and HELP output to not display the sendmail version.

The sendmail deamon has a history of security vulnerabilities. The recommendation is to change the default sendmail settings that display the sendmail version and other related information. Sendmail version information can be used by an attacker for fingerprinting purposes.

Solution

Create a backup copy of /etc/mail/sendmail.cf :

cp -p /etc/mail/sendmail.cf /etc/mail/sendmail.cf.pre_cis

Edit:

vi /etc/mail/sendmail.cf

Replace:

O SmtpGreetingMessage=$j Sendmail $b

With:

O SmtpGreetingMessage=mailerready
- Ensure Sendmail helpfile exists

test -e /etc/mail/helpfile || touch /etc/mail/helpfile

See Also

https://workbench.cisecurity.org/benchmarks/10385

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b.

Plugin: Unix

Control ID: 331a978912109ddb2d3de0e4fedaa8c85135c906d7550a4f639e23d0347496a4