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Fix Sudo Flaw CVE-2025-32463 Via Easy Rules, Detection, Response

Sudo Local Privilege Escalation Flaw CVE-2025-32463 Demands Immediate Attention

Posted on by Mike Shinn

By Michael Shinn

The CVE-2025-32463 Event

On Sept. 29, 2025, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) issued an alert as it added a critical security flaw that affects the sudo command line utility to its Known Exploited Vulnerabilities catalog. The sudo flaw is a local privilege escalation vulnerability (CVE-2025-32463) that impacts numerous Linux and Unix OSs, as well as macOS Sequoia.

Hacker - CVE-2025-32463 Exploit

The vulnerability was publicly disclosed by a researcher at Stratascale on or around June 30, 2025. NIST/NVD responded with initial tracking and analysis shortly after and then updated the record on July 17. CISA added CVE-2025-32463 to its Known Exploited Vulnerabilities (KEV) Catalog on September 29, 2025, after confirming evidence of its active exploitation in the wild.

Who and What Is Impacted by CVE-2025-32463?

CVE-2025-32463 impacts many Linux and Unix systems through sudo versions 1.9.14 to 1.9.17, and some earlier versions. Affected platforms include major Linux distributions like Ubuntu, Fedora, Debian, Red Hat, SUSE, and Amazon Linux 2023, as well as macOS Sequoia. This vulnerability allows local users to exploit the sudo chroot (-R) option to gain root privileges. Many organizations, including federal agencies, are urged by CISA to apply patches or mitigations to address this critical flaw.

Steps to Address Sudo Vulnerability CVE-2025-32463

You can also detect the sudo CVE attacks and automatically block them in real time with OSSEC. If you’re running Atomic OSSEC, you already have these protections, but if you’re not, here is how you can configure your systems so that OSSEC can automatically block these attacks in real time.

Step 1) Add auditd rules —
/etc/audit/rules.d/cve-2025-32463.rules

Drop this file in /etc/audit/rules.d/ and reload audit rules (augenrules --load or auditctl -R /etc/audit/rules.d/*.rules). Adjust arch=b64 to arch=b32 if you need 32-bit syscall coverage.

Shell

# Log every execution of sudo (executable run)
-a always,exit -F path=/usr/bin/sudo -F perm=x -k sudo_exec

# Capture sudo execve entries to collect argv
-a always,exit -F arch=b64 -S execve -F exe=/usr/bin/sudo -k sudo_execve

# (extra) watch for chroot usage attempts — execve events with sudo
-a always,exit -F arch=b64 -S execve -F exe=/usr/bin/sudo -k sudo_chroot

# Watch modifications of the canonical /etc/nsswitch.conf
-w /etc/nsswitch.conf -p wa -k nsswitch_mod

# Watch for creation/open of files named nsswitch.conf anywhere (open/openat/creat)
-a always,exit -F arch=b64 -S open,openat,creat -F name=nsswitch.conf -k rogue_nsswitch

# Watch for new/modified shared libraries in common lib paths
-w /usr/lib/ -p wa -k lib_watch
-w /lib/ -p wa -k lib_watch
-w /lib64/ -p wa -k lib_watch

Notes:

  • -k values are keys you can use with ausearch -k <key> to find events.
  • If you have additional paths that an attacker might drop .so files into (e.g., user-writable dirs you suspect), add targeted watches — avoid broad watches on /home unless necessary.

Step 2) Add OSSEC rules

Create the following XML file:

/var/ossec/etc/rules/999_cve_rules.xml

These rules expect OSSEC to be reading /var/log/audit/audit.log (default on many systems if auditd is enabled and OSSEC is configured to monitor it) and that you have the standard Atomic OSSEC rules, specifically the syslog rules.

XML

<group name="cve_2025_32463_auditd">

  <!-- Base: detect sudo execve with --chroot -->
  <rule id="100700" level="12">
    <if_sid>80700</if_sid>
    <field name="audit.exe">/usr/bin/sudo</field>
    <match>--chroot</match>
    <description>CVE-2025-32463 attempt detected: sudo with --chroot argument (from auditd)</description>
    <group>cve_2025_32463_base,auditd,privilege_escalation,sudo</group>
  </rule>

  <!-- Base: detect sudo execve with -R (shorthand) -->
  <rule id="100701" level="12">
    <if_sid>80700</if_sid>
    <field name="audit.exe">/usr/bin/sudo</field>
    <match>-R</match>
    <description>CVE-2025-32463 attempt detected: sudo with -R (shorthand chroot) argument (from auditd)</description>
    <group>cve_2025_32463_base,auditd,privilege_escalation,sudo</group>
  </rule>

  <!-- Prep: nsswitch.conf modification (prep/poisoning attempt) -->
  <rule id="100702" level="12">
    <if_sid>80700</if_sid>
    <!-- audit.path lines / PATH entries usually contain the filename, so simple match is fine -->
    <match>nsswitch.conf</match>
    <description>CVE-2025-32463 prep: nsswitch.conf modification detected (from auditd)</description>
    <group>cve_2025_32463_prep,auditd,config_change</group>
  </rule>

  <rule id="100703" level="12">
    <if_sid>80700</if_sid>
    <field name="audit.exe">/usr/bin/sudo</field>
    <match>/lib.*\.so\b</match>
    <description>CVE-2025-32463 prep: sudo referencing or modifying shared library (.so) in system lib path (from auditd)</description>
    <group>cve_2025_32463_prep,auditd,cve,library_modification</group>
  </rule>

  <!-- Repeated auditd attempts (audit-side correlation) -->
  <rule id="100704" level="14" frequency="2" timeframe="120">
    <if_matched_group>cve_2025_32463_base</if_matched_group>
    <description>Repeated CVE-2025-32463 sudo chroot attempts detected (auditd)</description>
    <group>cve,auditd,correlated,privilege_escalation,sudo</group>
  </rule>

  <!-- Cross-source correlation: auditd (base) + syslog sudo denial. -->
  <rule id="100705" level="15" timeframe="120">
    <if_matched_group>cve_2025_32463_base</if_matched_group>
    <if_matched_sid>100600</if_matched_sid>
    <description>CRITICAL: CVE-2025-32463 correlated sudo chroot attempt detected (auditd + syslog)</description>
    <group>cve,correlated,privilege_escalation,sudo,auditd,syslog</group>
  </rule>

</group>

Notes and tuning:

  • frequency/timeframe in the correlation rule means if both matched SIDs occur within timeframe seconds, increase confidence. Adjust these values to match your normal operations to reduce false positives.
  • Add field or match exceptions if you need to whitelist certain admin workflows or service accounts. You can also add <option>no_ar</option> to any rule to turn off active response for that rule.
  • Make sure you load these custom rules after your other OSSEC rules. These rules use earlier decoders and rules for auditd, sudo and syslog.

3) Optional OSSEC Active Response Snippets (in ossec.conf)

XML

<active-response>
  <command>firewall-drop</command>
  <location>local</location>
  <level>10</level>
  <timeout>600</timeout>
</active-response>

<active-response>
  <command>disable-account</command>
  <location>local</location>
  <level>12</level>
</active-response>

Recommendations:

  • You do not need to add these if you are using Atomic OSSEC.
  • Firewall-drop is the classic firewall script in all versions of OSSEC.
  • Use active responses only in lab or well-tested staging first. For high-impact systems, prefer notifications at high severity and manual remediation.

4) Commands to update sudo and verify the patched state (by distro)

The following are copy/paste blocks — run the block matching your OS. They update sudo and show how to verify the binary and package are patched.

Debian / Ubuntu

Shell

# Update sudo
sudo apt update
sudo apt install --only-upgrade -y sudo

# Verify
dpkg -l sudo
sudo --version
apt-cache policy sudo
# Optional: check changelog for CVE text
apt changelog sudo 2>/dev/null | grep -i '2025-32463\|CVE-2025-32463' || echo "no changelog mention found"

RHEL / Rocky / CentOS / AlmaLinux (yum/dnf)

Shell

# Update sudo
sudo dnf -y update sudo    # or sudo yum -y update sudo on older systems

# Verify
rpm -q sudo
/usr/bin/sudo --version
# Optional: inspect RPM changelog for CVE mention
rpm -q --changelog sudo | grep -i '2025-32463\|CVE-2025-32463' || echo "no changelog mention found"
# Optional: check updateinfo (if your system supports it)
sudo dnf updateinfo list cves | grep -i 2025-32463 || echo "no updateinfo entry found"

Fedora

Shell

sudo dnf -y update sudo
rpm -q sudo
sudo --version
rpm -q --changelog sudo | grep -i '2025-32463\|CVE-2025-32463' || echo "no changelog mention found"

SUSE / openSUSE

Shell

sudo zypper refresh
sudo zypper update -y sudo
zypper info sudo
/usr/bin/sudo --version
rpm -q --changelog sudo | grep -i '2025-32463\|CVE-2025-32463' || echo "no changelog mention found"

Amazon Linux (AL1/AL2/AL2023)

Shell

# AL1/AL2
sudo yum -y update sudo

# AL2023
sudo dnf -y update sudo

rpm -q sudo
/usr/bin/sudo --version

Alpine

Shell

sudo apk update
sudo apk add --upgrade sudo
apk info sudo
/usr/bin/sudo --version

Arch Linux

Shell

sudo pacman -Syu sudo
pacman -Qi sudo
/usr/bin/sudo --version

FreeBSD

Shell

sudo pkg update
sudo pkg upgrade sudo
pkg info sudo
/usr/local/bin/sudo --version

5) Post-patch validation & monitoring

  1. Confirm package version and/or vendor advisory states that CVE-2025-32463 is fixed. Vendor backports may not change the upstream version string. Always cross-check vendor security advisories. Atomic OSSEC will do this for you automatically, check your vulnerability reports in Atomic OSSEC.
  2. If you don’t have Atomic Inspector, use search logs for suspicious historical usage:
Shell

# Search audit logs for suspicious sudo execve with chroot
ausearch -k sudo_execve --start 2025-01-01 | aureport -f -i

# Search for nsswitch.conf writes
ausearch -k nsswitch_mod

# Search OSSEC alerts for the new rule IDs
grep -E "100500|100501|100502|100503|100504" /var/ossec/logs/alerts/alerts.log -n || echo "no matches"

       3. If you find evidence of exploitation or suspicious sequences, isolate the host, collect volatile data (ps, netstat/ss, /proc, kernel logs), preserve disk images, and notify the appropriate authorities.

Sudo Flaw CVE-2025-32463 Summary

Sudo local privilege escalation flaw CVE-2025-32463 demands immediate attention. Patch, block, or thwart sudo vulnerability exploits with OSSEC (refer to the above instructions). Alternatively, you can employ Atomic OSSEC to detect and automatically block these attempts in real time.

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