CVE-2017-9430 in dnstracer
Summary
by MITRE
Stack-based buffer overflow in dnstracer through 1.9 allows attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a command line with a long name argument that is mishandled in a strcpy call for argv[0]. An example threat model is a web application that launches dnstracer with an untrusted name string.
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Analysis
by VulDB Data Team • 06/25/2024
The vulnerability identified as CVE-2017-9430 represents a critical stack-based buffer overflow flaw within the dnstracer utility version 1.9 and earlier. This issue stems from improper input validation when processing command line arguments, specifically the argv[0] parameter, which creates a dangerous condition where attacker-controlled data can overwrite adjacent memory locations on the stack. The vulnerability manifests when a maliciously crafted command line argument containing an excessively long name string is passed to the application, causing the vulnerable strcpy function to copy data beyond the bounds of the allocated buffer. This fundamental flaw directly violates security principles by allowing arbitrary memory corruption that can lead to unpredictable application behavior and system instability.
The technical exploitation of this vulnerability occurs through a classic stack buffer overflow attack pattern where the strcpy function lacks proper bounds checking against the input data length. When an attacker supplies a command line argument exceeding the predetermined buffer size, the function continues writing beyond the allocated memory space, potentially overwriting return addresses, stack canaries, and other critical program state information. This type of vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is categorized under the broader weakness of insufficient boundary checking in memory operations. The attack vector becomes particularly dangerous when dnstracer is invoked by web applications or other automated systems that process untrusted input, as demonstrated in the threat model where a web application might launch the utility with user-provided name strings without adequate sanitization.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more sophisticated attacks depending on the execution environment and system protections in place. While the immediate effect is application crash and denial of service, the underlying buffer overflow creates opportunities for remote code execution if proper memory protection mechanisms like stack canaries, address space layout randomization, or non-executable stacks are not implemented. In environments where dnstracer is executed with elevated privileges or within automated web application workflows, this vulnerability could be leveraged to compromise the entire system. The threat model presented in the vulnerability description highlights a common attack scenario where web applications that invoke external utilities with untrusted input create an attack surface that directly exposes the system to buffer overflow exploitation techniques.
Mitigation strategies for CVE-2017-9430 should prioritize immediate patching of the dnstracer utility to a version that properly validates input lengths before processing. Organizations should implement defensive programming practices including the use of safer string handling functions such as strlcpy or strncpy instead of vulnerable strcpy operations, along with comprehensive input validation that enforces strict length limits on command line arguments. The solution should also include runtime protections such as stack canaries, address space layout randomization, and non-executable stack features to reduce the exploitability of any remaining buffer overflow conditions. Additionally, system administrators should consider implementing principle of least privilege for applications that invoke dnstracer, ensuring that the utility runs with minimal required permissions and that input validation is performed at multiple layers of the application stack. Network segmentation and monitoring should also be enhanced to detect potential exploitation attempts that may involve malformed command line arguments targeting this specific vulnerability. The remediation approach should align with industry best practices for buffer overflow prevention and follow the ATT&CK framework's guidance on defensive techniques for preventing command injection and memory corruption attacks that leverage similar vulnerabilities.