CVE-2017-13730 in ncurses
Summary
by MITRE
There is an illegal address access in the function _nc_read_entry_source() in progs/tic.c in ncurses 6.0 that might lead to a remote denial of service attack.
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Analysis
by VulDB Data Team • 01/10/2021
The vulnerability identified as CVE-2017-13730 resides within the ncurses library version 6.0, specifically in the progs/tic.c source file at the _nc_read_entry_source() function. This flaw represents a critical security issue that manifests as an illegal address access condition, potentially enabling remote attackers to execute denial of service attacks against systems utilizing affected versions of ncurses. The ncurses library serves as a fundamental component for terminal handling and screen rendering in Unix-like operating systems, making this vulnerability particularly concerning for system stability and availability.
The technical implementation of this vulnerability stems from improper input validation and memory management within the _nc_read_entry_source() function. When processing terminal capability entries, the function fails to adequately validate address boundaries and memory access patterns, leading to potential buffer overflows or invalid memory dereferences. This condition occurs during the parsing of terminal description files, where the library attempts to read and process terminal capability data. The flaw is categorized under CWE-125 as an out-of-bounds read, which allows attackers to manipulate memory access patterns through crafted terminal descriptions or capability files.
From an operational perspective, this vulnerability creates significant risk for systems that rely on ncurses for terminal interface functionality. Remote attackers can exploit this weakness by providing maliciously crafted terminal capability data to applications that utilize ncurses, potentially causing application crashes or system instability. The denial of service impact extends beyond individual applications to affect entire terminal sessions and potentially system services that depend on proper terminal handling. This vulnerability affects a wide range of systems including servers, workstations, and embedded devices that utilize ncurses for terminal interface management, making it particularly dangerous in enterprise and infrastructure environments where terminal access is prevalent.
The exploitation of this vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and can be classified under the broader category of privilege escalation attacks. Attackers typically leverage such flaws by crafting specially formatted terminal capability files or manipulating terminal description databases to trigger the illegal address access. The impact extends to system availability and service continuity, potentially affecting critical infrastructure components that depend on terminal handling capabilities. Organizations utilizing ncurses-based applications should consider this vulnerability as part of their broader security posture assessment, particularly in environments where terminal access and capability files are frequently updated or sourced from untrusted locations.
Mitigation strategies for CVE-2017-13730 primarily involve upgrading to patched versions of ncurses, specifically versions 6.1 or later where the vulnerability has been addressed through proper input validation and memory boundary checking. System administrators should implement strict access controls on terminal capability files and databases to prevent unauthorized modifications. Additionally, deploying network monitoring solutions that can detect anomalous terminal description file access patterns may provide early warning of potential exploitation attempts. Regular security audits of terminal handling components and comprehensive patch management programs are essential for maintaining system security. The vulnerability demonstrates the importance of rigorous input validation in system libraries and highlights the need for continuous security assessments of widely-used foundational components in operating system environments.