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XCCDF
IBM AIX 7.x Security Technical Implementation Guide
SRG-OS-000480-GPOS-00227
SMTP service must not have the EXPN or VRFY features active on AIX systems.
SMTP service must not have the EXPN or VRFY features active on AIX systems.
An XCCDF Rule
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SMTP service must not have the EXPN or VRFY features active on AIX systems.
Medium Severity
<VulnDiscussion>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. The VRFY (Verify) command allows an attacker to determine if an account exists on a system, providing significant assistance to a brute force attack on user accounts. VRFY may provide additional information about users on the system, such as the full names of account owners.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>