CVE-2016-10351 in Telegram
Summary
by MITRE
Telegram Desktop 0.10.19 uses 0755 permissions for $HOME/.TelegramDesktop, which allows local users to obtain sensitive authentication information via standard filesystem operations.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2016-10351 affects Telegram Desktop version 0.10.19 and represents a critical security flaw related to improper file system permissions. This issue stems from the application's failure to properly secure its configuration directory, specifically $HOME/.TelegramDesktop, which is created with overly permissive 0755 permissions. The root cause of this vulnerability aligns with CWE-732, which addresses incorrect permissions for critical security resources, and demonstrates a clear violation of the principle of least privilege in system security design. When an application creates directories with world-readable and world-executable permissions, it inadvertently provides unauthorized users with access to potentially sensitive data stored within those directories.
The technical flaw manifests through the exploitation of standard filesystem operations that allow local users to traverse the directory structure and access authentication-related files. The 0755 permission setting grants read, write, and execute permissions to the owner while providing read and execute permissions to group members and others, effectively enabling any local user to access the contents of the Telegram configuration directory. This misconfiguration creates a privilege escalation scenario where unauthorized users can potentially extract session tokens, encryption keys, or other sensitive authentication data that should remain protected within the application's secure storage area.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables local privilege escalation and potential credential theft. Attackers can leverage this weakness to obtain persistent access to user accounts, particularly when the application stores cached authentication tokens or session information in the insecurely configured directory. This vulnerability specifically aligns with ATT&CK technique T1003.001, which covers credential dumping, and represents a fundamental failure in application security hardening practices. The threat is particularly concerning in multi-user environments where one user could exploit this weakness to access another user's Telegram session data, potentially leading to account compromise and unauthorized communication activities.
Mitigation strategies for this vulnerability should focus on implementing proper file system permission controls and application security hardening measures. The recommended approach involves modifying the application's initialization routine to create the $HOME/.TelegramDesktop directory with restrictive permissions such as 0700, ensuring only the owner has read, write, and execute access. Security patches should enforce proper access control mechanisms through the use of umask settings and explicit permission management during directory creation. Additionally, the application should implement proper encryption for sensitive data stored in the configuration directory and regularly audit file system permissions to prevent similar issues from reoccurring. Organizations should also consider implementing monitoring solutions to detect unauthorized access attempts to sensitive directories and establish proper incident response procedures for handling such security incidents. This vulnerability demonstrates the critical importance of proper privilege management and access control implementation in client-side applications, particularly those handling sensitive communication data.