The SMTP service HELP command must not be enabled.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-220099	GEN004540	SV-220099r603266_rule		Medium

Description
The HELP command should be disabled to mask version information. The version of the SMTP service software could be used by attackers to target vulnerabilities present in specific software versions.

STIG	Date
Solaris 10 X86 Security Technical Implementation Guide	2020-12-04

Details

Check Text ( C-21808r489919_chk )
Check if Help is disabled in Sendmail. Procedure: # telnet 25 > help If the help command returns any Sendmail version information, this is a finding. If telnet is unavailable for testing, check the value of the HelpFile parameter in the sendmail.cf file. # grep HelpFile /etc/mail/sendmail.cf If the contents of the file indicated by the HelpFile parameter contains any Sendmail version information, this is a finding.

Check Text ( C-21808r489919_chk )

Check if Help is disabled in Sendmail.

Procedure:
# telnet 25
> help

If the help command returns any Sendmail version information, this is a finding.

If telnet is unavailable for testing, check the value of the HelpFile parameter in the sendmail.cf file.

# grep HelpFile /etc/mail/sendmail.cf

If the contents of the file indicated by the HelpFile parameter contains any Sendmail version information, this is a finding.

Fix Text (F-21807r489920_fix)
To disable the SMTP HELP command, clear the Sendmail help file. # echo > /etc/mail/helpfile