CVE-2017-9105 in adns
Summary
by MITRE
An issue was discovered in adns before 1.5.2. It corrupts a pointer when a nameserver speaks first because of a wrong number of pointer dereferences. This bug may well be exploitable as a remote code execution.
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Analysis
by VulDB Data Team • 05/15/2023
The vulnerability identified as CVE-2017-9105 affects the adns library version 1.5.1 and earlier, representing a critical memory corruption flaw that arises from improper pointer handling during DNS resolution processes. This issue specifically manifests when a nameserver responds to a query before the client has completed its request processing, creating a race condition that leads to incorrect pointer dereference operations within the library's internal memory management structures.
The technical root cause of this vulnerability stems from a fundamental error in how the adns library manages memory pointers when processing asynchronous DNS responses. When a nameserver initiates communication by sending a response before the client has properly established its query context, the library's pointer arithmetic becomes misaligned, resulting in memory corruption that can occur at multiple levels within the application's memory space. This misalignment creates a scenario where subsequent pointer operations may access invalid memory locations or overwrite critical data structures, fundamentally compromising the integrity of the application's execution environment.
The operational impact of CVE-2017-9105 extends beyond simple memory corruption, as the flaw presents a significant remote code execution vector that could be exploited by malicious actors. The vulnerability's exploitable nature stems from the fact that it occurs during normal DNS resolution operations, making it accessible to attackers who can craft malicious DNS responses to trigger the memory corruption. This represents a classic buffer overflow scenario where improper pointer dereferencing leads to arbitrary code execution, aligning with common attack patterns documented in the ATT&CK framework under the technique of code injection and memory corruption attacks.
Security researchers have classified this vulnerability under CWE-121, which deals with stack-based buffer overflow conditions, though the actual implementation involves heap corruption due to improper pointer management. The vulnerability's remote exploitation potential makes it particularly dangerous in networked environments where applications using the affected adns library might be exposed to untrusted DNS servers. This flaw can affect any application that relies on adns for DNS resolution, including web servers, mail servers, and network monitoring tools, making it a widespread concern across various system architectures.
Mitigation strategies for CVE-2017-9105 primarily involve upgrading to adns version 1.5.2 or later, which contains the necessary patches to address the pointer dereference issue. Organizations should also implement network segmentation and DNS server validation measures to limit exposure to potentially malicious DNS responses. The fix typically involves correcting the pointer arithmetic logic within the library's DNS response processing code, ensuring that pointer operations occur only after proper context establishment. Additionally, implementing proper input validation and memory bounds checking can provide additional defense-in-depth measures against similar vulnerabilities that may exist in other components of the system's DNS resolution stack.