Changes are coming to https://stigviewer.com.
Take our survey to help us understand your usage and how we can better serve you in the future.
Take Survey
The SMTP service must not have the EXPN feature active.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
|---|---|---|---|---|
| V-4692 | GEN004660 | SV-45872r1_rule | ECSC-1 | Low |
| Description |
|---|
| The SMTP EXPN function allows an attacker to determine if an account exists on a system, providing significant assistance to a brute force attack on user accounts. EXPN may also provide additional information concerning users on the system, such as the full names of account owners. |
| STIG | Date |
|---|---|
| SUSE Linux Enterprise Server v11 for System z | 2015-05-27 |
Details
| Check Text ( C-43189r1_chk ) |
|---|
| This vulnerability is applicable only to sendmail. If Postfix is the SMTP service for the system this will never be a finding. Procedure: Determine if EXPN is disabled. # grep -v "^#" /etc/mail/sendmail.cf |grep -i PrivacyOptions If nothing is returned or the returned line does not contain "noexpn", this is a finding. |
| Fix Text (F-39250r1_fix) |
|---|
| Rebuild /etc/mail/sendmail.cf with the "noexpn" Privacy Flag set. Procedure: Edit /etc/mail/sendmail.mc resetting the Privacy Flags to the default: define('confPRIVACYFLAGS', 'authwarnings,novrfy,noexpn,restrictqrun')dnl Rebuild the sendmail.cf file with: # make -C /etc/mail Restart the sendmail service. # service sendmail restart |