CVE-2019-15547 in ncurses Crate
Summary
by MITRE
An issue was discovered in the ncurses crate through 5.99.0 for Rust. There are format string issues in printw functions because C format arguments are mishandled.
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Analysis
by VulDB Data Team • 12/04/2023
The vulnerability identified as CVE-2019-15547 represents a critical format string vulnerability within the ncurses crate version 5.99.0 and earlier for the rust programming language. This issue arises from improper handling of C format arguments within the printw family of functions, creating a potential vector for arbitrary code execution and system compromise. The ncurses crate serves as a terminal handling library that provides text-based user interfaces and is widely used in rust applications requiring console interaction. The flaw specifically manifests when applications pass user-controlled data as format string arguments to functions like printw, which internally invoke C library functions without proper sanitization or validation of the format specifiers.
The technical implementation of this vulnerability stems from the crate's failure to properly escape or validate format string arguments before passing them to underlying C functions. When a rust application utilizing the ncurses crate calls printw with user-provided input containing format specifiers, the application becomes susceptible to format string attacks. This occurs because the crate does not implement proper input sanitization or argument validation mechanisms that would prevent malicious format specifiers from being interpreted by the underlying C library functions. The vulnerability is categorized under CWE-134 which specifically addresses format string vulnerabilities where format strings are constructed from user-controlled data without proper validation.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution and privilege escalation attacks. An attacker who can control input to printw functions could craft malicious format specifiers that read from arbitrary memory locations, write to arbitrary memory addresses, or even execute arbitrary code within the context of the vulnerable application. This presents significant security implications for applications that process untrusted input through ncurses interfaces, particularly server applications or command-line tools that accept user input for display operations. The vulnerability affects any rust application that uses the ncurses crate for terminal output and has not implemented additional input validation measures.
Mitigation strategies for CVE-2019-15547 involve multiple layers of defense including immediate version upgrades to ncurses crate versions that address the format string handling issues. System administrators and developers should prioritize updating to the patched versions of the crate to eliminate the vulnerability at its source. Additionally, implementing proper input validation and sanitization within applications that use the ncurses library can provide defense-in-depth measures. Applications should avoid passing untrusted user input directly to printw functions and instead use safer alternatives such as printf with explicit format strings or implement proper argument validation before processing user input through terminal display functions. The ATT&CK framework categorizes this vulnerability under T1059.007 for command and scripting interpreter usage, as exploitation may involve crafting malicious format strings to execute unintended commands or code within the vulnerable application context. Organizations should also consider implementing runtime monitoring and input validation mechanisms to detect and prevent exploitation attempts targeting this specific vulnerability.