CVE-2016-7553 in irssi
Summary
by MITRE
The buf.pl before 2.20 script in Irssi before 0.8.20 uses weak permissions for the scrollbuffer dump file created between upgrades, which might allow local users to obtain sensitive information from private chat conversations by reading the file.
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Analysis
by VulDB Data Team • 09/02/2020
The vulnerability identified as CVE-2016-7553 affects the Irssi IRC client software version 0.8.19 and earlier, specifically targeting the buf.pl script that handles scrollbuffer dump functionality. This issue represents a classic privilege escalation and information disclosure vulnerability that exploits weak file permissions to expose sensitive data. The vulnerability occurs during the upgrade process when the script creates a temporary scrollbuffer dump file that lacks proper security controls. The flaw stems from the script's failure to implement appropriate access controls on the temporary file, creating a window of opportunity for local attackers to access confidential chat conversations that were previously stored in the scrollbuffer. This vulnerability directly relates to CWE-732, which addresses inadequate permissions for critical resources, and aligns with ATT&CK technique T1005 for data from local systems and T1059 for command and scripting interpreter.
The technical implementation of this vulnerability involves the buf.pl script creating a temporary file during Irssi's upgrade process that contains the scrollbuffer data from previous conversations. When the script fails to set appropriate file permissions, it creates a file that can be read by any local user on the system. The scrollbuffer typically contains private chat messages, channel discussions, and other sensitive communications that users expect to remain confidential. Attackers can exploit this weakness by simply reading the dump file, which contains the conversation history without requiring any authentication or elevated privileges. The vulnerability demonstrates poor security hygiene in file handling and temporary file management practices within the software's upgrade mechanism. This type of flaw is particularly concerning in multi-user environments where local access might be granted to untrusted users or where privilege escalation opportunities exist within the system.
The operational impact of CVE-2016-7553 extends beyond simple information disclosure, as it can compromise the confidentiality of private communications and potentially expose sensitive information that might include personal details, business strategies, or other confidential data shared in chat conversations. The vulnerability affects all users running vulnerable versions of Irssi, making it a widespread concern for anyone using the software. The attack vector is relatively simple and does not require network access or complex exploitation techniques, making it particularly dangerous as it can be exploited by any local user with basic file system access. This vulnerability undermines user trust in the security of their communications and represents a failure in the software's security-by-design principles. Organizations using Irssi for sensitive communications or those with multi-user systems are particularly vulnerable to this type of attack, as the local access required for exploitation is often readily available. The issue also highlights the importance of proper file permission management and temporary file handling in security-critical applications.
Mitigation strategies for this vulnerability include immediately upgrading to Irssi version 0.8.20 or later, which contains the fix for this specific issue. System administrators should also implement proper file permission controls and audit temporary file usage patterns to prevent similar issues in other applications. The fix typically involves ensuring that any temporary files created during upgrade processes are created with restrictive permissions that prevent unauthorized access. Organizations should also consider implementing monitoring solutions to detect unauthorized access attempts to sensitive files and establish proper access controls for system users. Regular security audits of software installations can help identify other potential vulnerabilities in similar file handling patterns. Additionally, users should be educated about the importance of keeping their software updated and the risks associated with running outdated versions that may contain known vulnerabilities. The remediation process should also include verification that any existing dump files are properly secured or removed from the system to prevent ongoing exposure to this vulnerability.