CVE-2013-5580 in ngIRCd
Summary
by MITRE
The (1) Conn_StartLogin and (2) cb_Read_Resolver_Result functions in conn.c in ngIRCd 18 through 20.2, when the configuration option NoticeAuth is enabled, does not properly handle the return code for the Handle_Write function, which allows remote attackers to cause a denial of service (assertion failure and server crash) via unspecified vectors, related to a "notice auth" message not being sent to a new client.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 01/08/2022
The vulnerability identified as CVE-2013-5580 affects ngIRCd versions 18 through 20.2 and represents a critical denial of service flaw within the connection handling mechanism. This vulnerability specifically manifests in the Conn_StartLogin and cb_Read_Resolver_Result functions located in the conn.c source file. The issue occurs when the NoticeAuth configuration option is enabled, creating a scenario where the software fails to properly process the return code from the Handle_Write function. This improper error handling creates a condition where remote attackers can exploit the system by sending carefully crafted inputs that trigger an assertion failure, ultimately leading to a complete server crash and denial of service for legitimate users.
The technical root cause of this vulnerability stems from inadequate error code validation within the IRC daemon's connection management routines. When NoticeAuth is enabled, the software attempts to send authentication-related notice messages to new clients, but the failure to correctly evaluate the return value from Handle_Write creates a path for exploitation. This flaw represents a classic case of improper error handling that can be categorized under CWE-754, improper check for special error conditions, and more specifically aligns with CWE-248, an unchecked error condition. The vulnerability operates at the application layer and can be exploited through network-based attacks without requiring any authentication or privileges from the attacker.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by malicious actors to systematically degrade service availability for legitimate users. The assertion failure that occurs during the connection process creates a cascade effect that crashes the entire ngIRCd server instance, requiring manual restart and potentially causing extended downtime for IRC networks that rely on these services. This type of vulnerability is particularly concerning in network infrastructure services where continuous availability is critical, as it can be exploited to create persistent denial of service conditions that are difficult to detect and mitigate in real-time.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1499.004, Network Denial of Service, and demonstrates the importance of proper error handling in network services. The exploitability of this vulnerability is relatively straightforward, as it requires only network connectivity to the affected server and does not need specialized tools or privileged access. Organizations running ngIRCd with NoticeAuth enabled should consider this vulnerability as a high-priority concern, particularly in environments where network stability and uptime are mission-critical. The recommended mitigation strategy involves either disabling the NoticeAuth configuration option or applying the appropriate patches that correct the error handling logic in the affected functions, ensuring that return codes from Handle_Write are properly validated before proceeding with subsequent operations.