CVE-2001-0516 in Oracle
Summary
by MITRE
Oracle listener between Oracle 9i and Oracle 8.0 allows remote attackers to cause a denial of service via a malformed connection packet that contains an incorrect requester_version value that does not match an expected offset to the data.
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Analysis
by VulDB Data Team • 04/08/2019
The vulnerability described in CVE-2001-0516 represents a critical denial of service weakness within Oracle database listener components spanning versions 8.0 through 9i. This flaw exists in the listener service that facilitates communication between client applications and Oracle database servers, making it a prime target for remote exploitation. The vulnerability specifically affects the version negotiation process within the Oracle Net protocol implementation where the listener fails to properly validate incoming connection requests. When a remote attacker crafts a malicious connection packet with an incorrect requester_version value, the listener processes this malformed data without adequate validation, leading to system instability and potential service disruption. This issue demonstrates a fundamental flaw in input validation and error handling mechanisms within Oracle's network communication stack.
The technical root cause of this vulnerability lies in the Oracle listener's inadequate validation of the requester_version field within connection packets. According to CWE-20, this represents a classic input validation weakness where the system fails to properly sanitize or verify data received from external sources. The listener expects a specific offset value corresponding to the requester_version field, but when an attacker sends a packet with a mismatched version value, the system attempts to process the data using an incorrect offset calculation. This misalignment causes the listener to either crash or become unresponsive, effectively rendering the database service unavailable to legitimate users. The flaw operates at the protocol level within Oracle's Net Services implementation, specifically affecting the connection establishment phase where version compatibility checks occur.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the availability of critical database infrastructure. Organizations running Oracle databases between versions 8.0 and 9i face significant risk when exposed to unauthenticated remote attackers who can exploit this weakness to cause sustained denial of service attacks. The vulnerability can be exploited repeatedly without requiring authentication, making it particularly dangerous in environments where database listeners are exposed to untrusted networks. Attackers can cause intermittent service outages or complete system shutdowns by simply sending malformed packets, potentially leading to business disruption and financial losses. This weakness also enables attackers to perform reconnaissance activities by testing system responses to malformed packets, potentially identifying other vulnerabilities within the Oracle ecosystem.
Mitigation strategies for CVE-2001-0516 should focus on both immediate defensive measures and long-term architectural improvements. Organizations should implement network segmentation to restrict access to Oracle listener ports, typically port 1521, limiting exposure to trusted networks only. The most effective immediate solution involves applying Oracle's official security patches and updates that address the version validation logic within the listener component. Network administrators should also configure firewalls and intrusion detection systems to monitor and filter suspicious connection attempts that contain malformed requester_version values. According to ATT&CK framework category T1498, this vulnerability aligns with denial of service tactics that organizations should defend against through proper network architecture and access control measures. Regular security assessments and vulnerability scanning should be implemented to identify systems running vulnerable Oracle versions, while also ensuring that all database components are kept up to date with the latest security patches. The remediation process requires careful planning to avoid disrupting legitimate database operations during patch deployment, particularly in production environments where database availability is critical.