CVE-2017-2909 in Mongoose
Summary
by MITRE
An infinite loop programming error exists in the DNS server functionality of Cesanta Mongoose 6.8 library. A specially crafted DNS request can cause an infinite loop resulting in high CPU usage and Denial Of Service. An attacker can send a packet over the network to trigger this vulnerability.
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Analysis
by VulDB Data Team • 01/06/2023
The vulnerability identified as CVE-2017-2909 represents a critical programming flaw within the Cesanta Mongoose 6.8 web server library that specifically affects DNS server functionality. This issue manifests as an infinite loop condition that occurs when processing specially crafted DNS requests, creating a scenario where the affected system becomes trapped in continuous processing cycles without proper termination. The vulnerability resides in the library's DNS handling code, which fails to properly validate or sanitize incoming DNS query packets before processing them. This type of flaw falls under CWE-835, which specifically addresses the issue of infinite loops or iterations without proper exit conditions, making it a classic example of a denial of service vulnerability that can be exploited remotely.
The technical implementation of this vulnerability demonstrates how malformed DNS packets can trigger a cascade of recursive processing that never reaches a termination point. When the Mongoose library receives a DNS request that contains specific malformed data patterns, the parsing logic enters an infinite loop where it continuously processes the same packet or set of packet data without advancing to the next stage of processing. This behavior results in sustained high CPU utilization as the processor remains occupied with the same computational tasks indefinitely. The attack vector requires only a simple network packet transmission, making it particularly dangerous as it can be executed by any remote attacker without requiring authentication or privileged access to the target system. Network-based attacks exploiting this vulnerability can effectively render the affected service unusable and consume all available processing resources.
The operational impact of CVE-2017-2909 extends beyond simple service disruption to potentially compromise entire network infrastructure that relies on the affected Mongoose library. Systems running applications built on this library become vulnerable to sustained denial of service attacks that can exhaust system resources and cause cascading failures. The vulnerability affects any environment where the Cesanta Mongoose 6.8 library is deployed as a DNS server component, including embedded systems, IoT devices, and network appliances that utilize this popular lightweight web server library. Organizations using this library in production environments face significant risk of service unavailability and potential business disruption, as the infinite loop can be triggered by a single malicious packet. The vulnerability also aligns with ATT&CK technique T1499.004, which describes denial of service attacks through resource exhaustion, making it particularly concerning for network infrastructure and service providers.
Mitigation strategies for CVE-2017-2909 require immediate action to address the root cause through software updates and code modifications. The primary solution involves upgrading to a patched version of the Cesanta Mongoose library that contains proper input validation and loop termination logic for DNS request processing. Organizations should implement network-level filtering to detect and block malformed DNS traffic patterns that could trigger the infinite loop condition. Additionally, system administrators should monitor CPU usage patterns for unusual spikes that might indicate exploitation attempts, and implement proper rate limiting on DNS query processing to prevent sustained exploitation. The vulnerability highlights the importance of proper input validation and defensive programming practices, particularly in network services that handle external data inputs. Security monitoring solutions should be configured to detect anomalous processing behavior that could indicate the presence of this vulnerability, and regular security assessments should verify that all instances of the affected library have been properly updated to prevent exploitation.