CVE-1999-0682: Medium severity Microsoft Exchange Server vulnerability
Microsoft Exchange 5.5 allows a remote attacker to relay email (i.e. spam) using encapsulated SMTP addresses, even if the anti-relaying features are enabled.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Configure Exchange to require SMTP authentication for all relaying and explicitly limit which IP addresses or hosts are permitted to relay mail. Verify and tighten any anti-relay settings to minimize exposure to encapsulated-address bypasses.
Microsoft Exchange Server SMTP relay restrictions / authentication = require authentication; restrict relay to explicit IP allowlist - Compensating control
Restrict inbound SMTP access to the affected Exchange 5.5 servers at the network perimeter. Allow SMTP only from trusted mail relays or specific IP ranges and block direct SMTP connections from the public Internet to prevent abuse via encapsulated SMTP addresses.
- Operational
Monitor mail queues and server logs for signs of open-relay or spam relaying activity (including messages using encapsulated SMTP addresses). Investigate and remediate any observed abuse, and apply any vendor-supplied fixes if/when they become available.
Event History
Frequently Asked Questions
What is the severity of CVE-1999-0682?
CVE-1999-0682 is considered a significant vulnerability that allows remote email relaying, potentially leading to spam abuse.
How do I fix CVE-1999-0682?
To mitigate CVE-1999-0682, ensure that anti-relaying features in Microsoft Exchange 5.5 are properly configured and consider implementing additional security measures.
Which versions of Microsoft Exchange are affected by CVE-1999-0682?
CVE-1999-0682 affects Microsoft Exchange Server 5.5, including Service Packs 1 and 2.
What is the impact of CVE-1999-0682?
The impact of CVE-1999-0682 is the ability for attackers to relay emails without proper authorization, leading to potential spam outbreaks.
Is it possible to disable the relaying feature to prevent CVE-1999-0682?
Yes, disabling the relaying feature in Microsoft Exchange server settings can help prevent exploitation of CVE-1999-0682.