How to Easily Escalate to Root on Linux Using the Latest Sudo Vulnerabilities

A newly disclosed pair of critical vulnerabilities in Sudo — the powerful Unix/Linux command-line tool that allows users to run commands as root — poses a significant local privilege escalation threat. These flaws impact major Linux distributions and allow unprivileged local users to gain root access, thereby compromising system integrity.

Summary of the Vulnerabilities

The vulnerabilities are tracked as:

• CVE-2025-1013
• CVE-2025-1014

They affect Sudo versions from 1.9.0 to 1.9.15p1 and exploit how Sudo handles certain I/O logging functionality and user privileges. Both issues have been fixed in Sudo 1.9.15p2.

Technical Overview

CVE-2025-1013 — I/O Logging Plugin Abuse (Local Privilege Escalation)

Vulnerability Type:

Improper handling of I/O plugin environment variables in Sudo’s configuration, specifically SUDOERS_IO_PLUGIN.

Technical Description:

Sudo can be configured with I/O logging, which logs the user’s input/output during command execution. A plugin (usually /usr/libexec/sudo/sudo_logsrvd or similar) is specified to handle this.

In vulnerable versions (1.9.0 to 1.9.15p1), users with limited sudo rights can exploit a race condition or environmental variable manipulation to inject arbitrary paths or binaries as the I/O plugin.

This allows an attacker to force sudo to:

• Load a malicious shared library
• Or execute a custom binary with root privileges

Exploitation Steps (Simplified):

1. Attacker has access to a non-root user that can run some limited sudo command (e.g., sudo ls, sudo less, etc.).
2. The system is configured to use an I/O plugin.
3. Attacker sets the SUDOERS_IO_PLUGIN environment variable to a path pointing to their malicious shared object or script.
4. Sudo, under misconfiguration, uses this attacker-controlled plugin without validating ownership or context.
5. The malicious plugin gets executed with UID 0 (root).

🧪Example:

export SUDOERS_IO_PLUGIN=/home/user/malicious_plugin.so
sudo ls  # or any sudo-allowed command

This causes malicious_plugin.so to be loaded and executed as root.

Impact:

• Complete local privilege escalation.
• No kernel exploit required.
• Can be used in post-exploitation or lateral movement scenarios.

CVE-2025-1014 — Policy Plugin Privilege Confusion

Vulnerability Type:

Improper state management in the way Sudo interacts with policy plugins, particularly in multi-phase authentication and session management.

Technical Description:

Sudo relies on policy plugins (like the default sudoers) to determine what commands a user is authorized to run. However, vulnerable versions fail to consistently enforce authorization state across plugin calls, leading to authorization confusion.

An attacker can:

• Trigger a privileged operation using a benign, allowed command.
• Midway, manipulate the plugin interaction (via sudoedit, signal handling, or crafted inputs) to trick sudo into escalating privileges for a command that was not permitted.

The attacker leverages incomplete isolation between sessions or subprocesses, allowing them to reuse elevated context for unauthorized actions.

Exploitation Example:

Suppose a user is allowed to run:

sudoedit /etc/motd

But is not allowed to run arbitrary binaries. By chaining processes or modifying temporary files used during sudoedit, the attacker could trick Sudo into executing another binary (e.g., /bin/bash) with root privileges.

Steps in practice:

1. Invoke sudoedit on a controlled file.
2. Swap symlink or modify the file in transit (race condition).
3. Inject shell command or redirect execution flow.
4. Gain a root shell.

Use Case:

sudoedit /tmp/fakefile
# Meanwhile, attacker replaces /tmp/fakefile with a symlink to /etc/shadow

Or leverage crafted EDITOR environment variables:

EDITOR='bash -c "cp /bin/bash /tmp/rootbash; chmod +s /tmp/rootbash"' sudoedit /etc/hosts
/tmp/rootbash  # Now has root privileges

Note: This depends on how environment variables are handled in sudoers and may need env_keep permissions.

Summary: Exploitation Matrix

CVE	Required Access	User Interaction	Privilege Escalation	Exploitable From	Remote?
CVE-2025-1013	Local User	Some sudo rights	Full root via plugin hijack	Shell/CLI	No
CVE-2025-1014	Local User	sudoedit allowed	Full root via auth state bypass	Shell/Editor	No

Affected Systems

The vulnerabilities affect major distributions, including but not limited to:

• Debian
• Ubuntu
• Red Hat Enterprise Linux (RHEL)
• Fedora
• Arch Linux

Organizations using Linux-based infrastructure — whether for DevOps, containers, or internal systems — are strongly advised to assess exposure immediately.

Mitigation and Recommendations

Immediate Actions:

• Upgrade to Sudo 1.9.15p2, which patches both CVEs.
• Audit sudoers configurations to:
  • Minimize ALL command privileges.
  • Disable untrusted plugins or I/O logging features if not needed.
• Monitor for unexpected sudo command usage in logs.

Detection Tactics:

• Use EDR tools to monitor for escalation attempts via sudo -e or plugin abuse.
• Watch for creation of unusual log files or plugin paths being called dynamically.

Key Reflections for Cybersecurity Teams

1. Plugins = Power + Risk

Sudo’s plugin-based extensibility introduces opportunities for attack when not tightly controlled. Organizations should harden configurations and disable unused plugin interfaces.

2. Local != Safe

Many environments assume local users are low risk. These CVEs reinforce the need for zero-trust principles, even within internal environments or trusted shells.

3. Supply Chain Context

If containers or virtual machines embed outdated versions of Sudo, this vulnerability could be leveraged as a pivot point for lateral movement or breakout in multi-tenant systems.