Detect Linux Kernel Integer Overflow in create_elf_tables (CVE-2018-14634) in Splunk
CVE-2018-14634 is an integer overflow vulnerability in the Linux kernel's create_elf_tables() function, triggered during process execution via the execve syscall. A local unprivileged attacker can exploit this flaw to achieve privilege escalation to root by crafting a binary with an extremely large argument list. This vulnerability exists in Linux kernel versions 2.6.x through 4.14.x and is listed in CISA's Known Exploited Vulnerabilities catalog.
MITRE ATT&CK
- Tactic
- Privilege Escalation
SPL Detection Query
index=linux_audit sourcetype=linux_audit action=execve
| eval arg_count=mvcount(a0)
| where arg_count > 100
| join type=left uid [
search index=linux_audit sourcetype=linux_audit syscall=setuid OR syscall=setreuid OR syscall=setresuid success=yes
| where uid=0 OR euid=0
| table uid, _time, syscall, euid
]
| where isnotnull(euid) AND euid=0
| stats count min(_time) as first_seen max(_time) as last_seen values(a0) as commands by uid, host
| where count > 0
| eval severity="critical"
| table _time, host, uid, commands, euid, severityDetects exploitation attempts of CVE-2018-14634 by identifying execve syscalls with abnormally large argument counts (potential trigger condition) followed by unexpected privilege escalation to root on Linux systems via auditd logs.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Legitimate applications that spawn processes with many arguments such as build systems
- Configuration management tools like Ansible or Chef executing complex commands
- Container runtimes that pass large environment variable sets to new processes
- Scripted automation that legitimately escalates privileges via sudo
Other platforms for CVE-2018-14634
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Simulate Large Argument execve Invocation
Expected signal: Auditd logs an execve syscall record with an unusually large a1 or args array. Process creation event logged with high argument count.
- Test 2Check for Vulnerable Kernel Version
Expected signal: Process execution of uname and package manager commands logged via auditd or endpoint telemetry.
- Test 3Exploit Binary Drop and Execute Simulation (Lab Only)
Expected signal: File creation in /tmp, chmod syscall, bash script execution, and id command execution all logged via auditd. File write to /tmp from a non-root user.
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