Linux Kernel perf_event_open Integer Validation Vulnerability leading to Local Privilege Escalation (CVE-2013-2094)
Executive & SecOps Summary
SECOPS ASSESSMENTLinux kernel versions 2.6.37 through 3.8.8
Local unprivileged users can exploit this vulnerability via a crafted perf_event_open system call to execute arbitrary code with root privileges
Upgrade the Linux kernel to version 3.8.9 or higher, or restrict unprivileged access to performance events by configuring perf_event_paranoid
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the official vendor updates to upgrade the Linux kernel to a non-vulnerable version (3.8.9 or later).
# For RHEL/CentOS systems
sudo yum update -y kernel
sudo reboot
# For Ubuntu/Debian systems
sudo apt-get update
sudo apt-get install --only-upgrade -y linux-image-generic
sudo reboot2. Temporary Workaround & Hardening Configuration
If an immediate reboot is not feasible, mitigate the risk by disabling unprivileged access to the performance event subsystem.
# Set perf_event_paranoid to 2 to restrict unprivileged access immediately
sudo sysctl -w kernel.perf_event_paranoid=2
# Persist the configuration across reboots
echo 'kernel.perf_event_paranoid = 2' | sudo tee -a /etc/sysctl.conf3. Log Audit & IoC Verification Commands
Verify the current kernel version and check if the mitigation is active on the system.
# Check the running kernel version
uname -r
# Verify the current status of the perf_event_paranoid parameter
PARANOID_STATUS=$(sysctl -n kernel.perf_event_paranoid)
echo 'Current perf_event_paranoid level is:' $PARANOID_STATUS
if [ '$PARANOID_STATUS' -lt 2 ]; then
echo '[ALERT] System may be vulnerable if running an unpatched kernel.'
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Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2013-2094) is a critical integer validation flaw (CWE-189) located within the performance monitoring subsystem (perf) of the Linux kernel. Specifically, in kernel/events/core.c, the perf_swevent_init function incorrectly handles the event ID passed from user space. The function assigns a 64-bit unsigned integer (u64) event configuration value to a 32-bit signed integer (int) variable. This type mismatch leads to integer truncation and signedness issues, allowing the validation checks to be bypassed.
2. Exploitation Mechanics & Attack Scenario
An attacker with local, non-privileged access invokes the perf_event_open system call. By passing a carefully crafted, extremely large 64-bit value in the config field of the perf_event_attr structure, the attacker triggers the integer truncation during the type casting in perf_swevent_init. Because the truncated value passes the boundary checks, it is subsequently used as an index for an array lookup. This results in an out-of-bounds write relative to the kernel's static software event array. By precisely calculating the offset, the attacker can overwrite critical kernel memory structures, such as the current process's credential structure (cred), resetting the UID and GID to 0 (root).
3. Infrastructure & Business Impact
As a highly reliable and publicly exploited vulnerability listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, CVE-2013-2094 poses a severe threat to legacy systems and container hosts. In multi-tenant cloud environments or shared hosting servers, a compromise of a single unprivileged container or user account can lead to a complete host takeover, bypassing all logical isolation boundaries.
Official Vendor Advisories & References
The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9 uses an incorrect integer data type, which allows local users to gain privileges via a crafted perf_event_open system call.
Frequently Asked SecOps Questions (CVE-2013-2094)
FAQQ1. How critical is CVE-2013-2094 and is it actively exploited in the wild?
CVE-2013-2094 is rated CVSS 8.4 (HIGH) with a 30-day EPSS exploitation probability of 47.7%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2013-2094?
Primary impacted vendors include linux across linux_kernel. Scope summary: Linux kernel versions 2.6.37 before 3.8.9, affecting major enterprise distributions of that era including RHEL 6, CentOS 6, Debian, and Ubuntu
Q3. What temporary mitigations or workarounds exist for CVE-2013-2094 before patching?
[Mitigation] Upgrade the Linux kernel to version 3.8.9 or higher, or restrict unprivileged access to performance events by configuring perf_event_paranoid Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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