CVE-2002-2271 in IRC Client
Summary
by MITRE
Buffer overflow in BigFun 1.51b IRC client, when the Direct Client Connection (DCC) option is used, allows remote attackers to cause a denial of service (crash) via a long string.
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Analysis
by VulDB Data Team • 04/20/2019
The vulnerability identified as CVE-2002-2271 represents a critical buffer overflow flaw within the BigFun 1.51b IRC client software, specifically manifesting when the Direct Client Connection DCC feature is activated. This vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, where insufficient bounds checking allows an attacker to write beyond the allocated memory buffer. The DCC functionality in IRC clients enables direct file transfers and chat connections between users, making it a commonly used feature that presents a significant attack surface when improperly implemented.
The technical implementation of this vulnerability occurs when the BigFun IRC client processes incoming DCC requests containing excessively long string data. During normal operation, the client allocates a fixed-size buffer to store incoming data from DCC connections, but fails to validate the length of incoming strings before copying them into this buffer. When an attacker crafts a malicious DCC request with a string that exceeds the buffer capacity, the overflow occurs and overwrites adjacent memory locations, potentially corrupting program execution flow and causing the application to crash or behave unpredictably. This particular implementation flaw demonstrates poor input validation practices that are commonly exploited in network-based attacks.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged to potentially execute arbitrary code or cause persistent system instability within the affected IRC client environment. Attackers can exploit this weakness by connecting to a vulnerable BigFun client and initiating a DCC transfer with specially crafted malicious data. The crash typically manifests as an immediate application termination, rendering the IRC client unusable for the affected user and potentially disrupting collaborative communication channels where the client is being used. This vulnerability particularly affects environments where users frequently engage in DCC transfers or where the software is deployed in shared or public computing environments where untrusted users might have access to the client.
Mitigation strategies for this vulnerability should include immediate software updates from the vendor to patch the buffer overflow implementation, along with network-level controls that restrict DCC functionality in high-risk environments. Security practitioners should implement network segmentation to limit exposure of vulnerable IRC clients and consider disabling DCC features entirely if not essential for operations. The ATT&CK framework categorizes this vulnerability under T1203 Exploitation for Client Execution and T1068 Exploitation for Privilege Escalation, emphasizing the need for proper input validation and memory management practices. Organizations should also consider implementing network monitoring to detect unusual DCC traffic patterns that might indicate exploitation attempts, while ensuring that all client software versions are regularly updated to address known vulnerabilities. The vulnerability underscores the importance of adhering to secure coding practices such as those recommended in the OWASP Secure Coding Practices and the CERT/CC Secure Coding Standards, particularly regarding bounds checking and memory management in networked applications.