CVE-2017-15723 in irssi
Summary
by MITRE
In Irssi before 1.0.5, overlong nicks or targets may result in a NULL pointer dereference while splitting the message.
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Analysis
by VulDB Data Team • 01/19/2021
The vulnerability identified as CVE-2017-15723 affects Irssi, a popular console-based IRC client, specifically versions prior to 1.0.5. This issue represents a classic buffer overflow condition that manifests through improper handling of excessively long nicknames or target identifiers during message processing. The flaw occurs within the client's message splitting mechanism when it encounters overlong identifiers that exceed the system's expected buffer limits. Such conditions can arise when users join IRC channels with extremely long nicknames or when the client processes messages containing malformed or excessively lengthy target specifications.
The technical implementation of this vulnerability stems from insufficient input validation and boundary checking within Irssi's message parsing routines. When the client encounters a nickname or target that exceeds predetermined length thresholds, the internal string handling functions fail to properly manage the overflow condition, leading to a NULL pointer dereference. This occurs because the software attempts to access memory locations that have not been properly allocated or initialized, causing the application to crash or behave unpredictably. The vulnerability specifically impacts the client's ability to process and display messages containing such malformed identifiers, creating a denial of service condition that affects the entire IRC session.
The operational impact of CVE-2017-15723 extends beyond simple service disruption to potentially compromise the integrity of IRC communications. Attackers could exploit this vulnerability by crafting malicious nicknames or target identifiers that trigger the NULL pointer dereference, effectively causing the victim's Irssi client to crash and terminate the connection to IRC networks. This type of denial of service attack can be particularly disruptive in collaborative environments where multiple users rely on stable IRC connections for communication. The vulnerability may also enable more sophisticated attacks if the crash conditions can be leveraged to execute arbitrary code or manipulate the client's memory state, though the direct exploitability for code execution remains limited without additional attack vectors.
This vulnerability aligns with CWE-476, which addresses NULL pointer dereference conditions, and demonstrates poor input validation practices that violate fundamental security principles. From an ATT&CK framework perspective, this issue maps to the T1499.004 technique related to network denial of service, where adversaries can disrupt services through malformed input processing. The vulnerability also reflects weaknesses in software design patterns that fail to implement proper bounds checking and memory management protocols. Organizations using Irssi should implement immediate patch management procedures to upgrade to version 1.0.5 or later, which includes proper input validation and buffer overflow protection mechanisms. Additionally, network administrators should monitor for unusual connection patterns or client crashes that might indicate exploitation attempts, while developers should adopt defensive programming practices including comprehensive input sanitization and robust error handling to prevent similar issues in future implementations.