CVE-2007-1400 in Plesh
Summary
by MITRE
Plash permits sandboxed processes to open /dev/tty, which allows local users to escape sandbox restrictions and execute arbitrary commands by sending characters to a shell process on the same termimal via the TIOCSTI ioctl.
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Analysis
by VulDB Data Team • 10/12/2017
The vulnerability described in CVE-2007-1400 represents a critical sandbox escape mechanism within the plash sandboxing framework that was designed to isolate processes from each other and from the underlying system. This flaw specifically targets the security model of plash, which aims to provide a restricted execution environment for applications while maintaining system integrity. The vulnerability arises from an improper handling of terminal device access permissions, creating a pathway for privilege escalation that undermines the fundamental security assumptions of the sandbox architecture. The issue is particularly concerning because it allows local users to bypass the sandbox restrictions that are meant to contain potentially malicious or untrusted processes.
The technical exploitation of this vulnerability hinges on the ability of a sandboxed process to open the /dev/tty device node, which provides access to the controlling terminal of the process. This access point is not properly restricted within the plash environment, enabling malicious code to leverage the TIOCSTI ioctl command to inject characters into the terminal input buffer. The TIOCSTI ioctl allows a process to simulate terminal input by injecting keystrokes into the terminal's input queue, effectively enabling an attacker to send commands to running shell processes. When combined with the ability to open /dev/tty, this creates a direct pathway for arbitrary command execution on the host system, completely bypassing the sandbox isolation mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation to represent a complete breakdown of the sandbox security model. Local users can leverage this flaw to execute arbitrary commands with the privileges of the sandboxed process, which may be running with elevated permissions or access to sensitive system resources. The attack vector is particularly insidious because it requires no network connectivity or remote exploitation capabilities, making it a significant concern for systems that rely on sandboxing for security isolation. The vulnerability affects systems where plash is used to execute untrusted code in restricted environments, potentially exposing sensitive data and system resources to unauthorized access.
This vulnerability aligns with CWE-284, which addresses improper access control mechanisms, and demonstrates how insufficient device access controls can lead to complete system compromise. From an ATT&CK perspective, this represents a privilege escalation technique using TIOCSTI ioctl commands to inject input into terminal sessions, falling under the T1068 privilege escalation tactics. The flaw also relates to T1548.001 which covers abuse of system permissions and T1059 which covers command and scripting interpreters. Effective mitigations require strict device access controls and the removal of unnecessary terminal device access from sandboxed processes. System administrators should implement proper access control lists and consider alternative sandboxing mechanisms that do not expose terminal devices to untrusted processes. Regular auditing of device access permissions and monitoring for suspicious terminal activity can help detect exploitation attempts, while patching the underlying plash implementation to properly restrict access to /dev/tty and associated ioctl commands remains the most effective long-term solution to prevent this class of sandbox escape attacks.