CVE-2018-19217 in ncurses
Summary
by MITRE
In ncurses 6.1, there is a NULL pointer dereference at the function _nc_name_match that will lead to a denial of service attack.
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2018-19217 affects the ncurses library version 6.1, specifically within the _nc_name_match function where a NULL pointer dereference occurs. This flaw represents a classic denial of service condition that can be exploited by malicious actors to disrupt system operations. The ncurses library serves as a fundamental component for terminal handling and user interface development across numerous Unix-like operating systems and applications, making this vulnerability particularly concerning from a security perspective. The issue manifests when the function attempts to dereference a pointer that has not been properly validated, leading to a crash of the affected process. This type of vulnerability falls under the category of improper input validation and memory management errors, which are commonly classified under CWE-476 in the Common Weakness Enumeration catalog. The attack vector for this vulnerability typically involves crafted input that triggers the problematic code path within the terminal handling routines, potentially affecting applications that rely on ncurses for their user interface components.
The operational impact of CVE-2018-19217 extends beyond simple service disruption, as it can compromise the stability of terminal-based applications and system services that depend on ncurses functionality. When exploited, the NULL pointer dereference causes an application to terminate unexpectedly, potentially leaving users with incomplete or failed terminal sessions. This denial of service condition can be particularly damaging in server environments where terminal-based management interfaces are critical for system administration tasks. The vulnerability is especially problematic because ncurses is widely used across different software packages including shell environments, text editors, system monitoring tools, and various administrative utilities. Attackers can leverage this weakness to target specific applications or cause broader system instability by exploiting the library's widespread usage. The vulnerability's exploitation does not typically require elevated privileges, making it accessible to less privileged users and increasing the potential attack surface. This characteristic aligns with ATT&CK technique T1499.004 which focuses on network denial of service attacks and system resource exhaustion.
Mitigation strategies for CVE-2018-19217 primarily involve updating to patched versions of the ncurses library, with version 6.1-20181027 and later containing the necessary fixes. System administrators should prioritize patching affected systems, particularly those running terminal-based applications or services that depend on ncurses functionality. The fix implemented by the ncurses maintainers addresses the NULL pointer dereference by adding proper validation checks before pointer access, ensuring that the _nc_name_match function handles edge cases gracefully. Organizations should also implement monitoring for abnormal application termination patterns that could indicate exploitation attempts. Additional defensive measures include restricting input validation for terminal applications and employing sandboxing techniques where appropriate. The vulnerability demonstrates the importance of proper memory management practices and input validation in system libraries, reinforcing the need for comprehensive code review processes and regular security updates. Security teams should consider this vulnerability as part of their broader assessment of terminal handling components and ensure that all dependencies are kept current with security patches. The remediation process should also include testing of patched applications to verify that the fix does not introduce regressions in functionality. Organizations using legacy systems may need to implement additional controls such as application whitelisting or network segmentation to limit potential exploitation vectors while longer-term patching strategies are implemented.