Detect GNU InetUtils Argument Injection Vulnerability (CVE-2026-24061) in Splunk
CVE-2026-24061 is an argument injection vulnerability (CWE-88) in GNU InetUtils affecting utilities such as telnet, ftp, rsh, rcp, and related tools. An attacker who can control arguments passed to InetUtils binaries may inject additional command-line options, potentially enabling unauthorized network access, privilege escalation, or lateral movement. This vulnerability is listed on the CISA Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
MITRE ATT&CK
SPL Detection Query
index=* sourcetype IN ("linux_audit", "syslog", "WinEventLog:Security", "xmlwineventlog")
("telnet" OR "ftp" OR "rsh" OR "rcp" OR "rlogin" OR "tftp")
| eval cmd=coalesce(CommandLine, process, message)
| where match(cmd, "(?i)(telnet|ftp|rsh|rcp|rlogin|tftp)")
| where match(cmd, "(?i)(-[a-zA-Z]{1,3}=|%0[aAdD]|\\\\x[0-9a-fA-F]{2}|;\\s*(bash|sh|nc|curl|wget|python|perl)|\\\\n|\\\\r)")
| eval risk_score=case(
match(cmd, "(?i)(bash|sh|nc|curl|wget|python|perl)"), 90,
match(cmd, "%0[aAdD]"), 80,
match(cmd, "-[a-zA-Z]{1,3}="), 60,
true(), 50
)
| eval injected_arg=mvindex(split(cmd, " "), 2)
| table _time, host, user, cmd, injected_arg, risk_score
| sort - risk_score, _timeSplunk query detecting argument injection attempts against GNU InetUtils binaries by correlating process execution logs across Linux audit, syslog, and Windows event sources for suspicious option-injection patterns.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Network operations scripts that pass complex argument strings to FTP or Telnet for automated transfers
- Penetration testing tooling that legitimately exercises InetUtils argument parsing
- Configuration management pipelines using InetUtils for connectivity testing with non-standard flags
- Legacy backup or monitoring scripts invoking rcp or rsh with concatenated argument strings
Other platforms for CVE-2026-24061
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 1InetUtils telnet argument injection via newline encoding
Expected signal: Auditd EXECVE record showing argv[1] containing a newline character followed by '-l root'; process event logs capturing the raw command-line string with embedded newline.
- Test 2InetUtils ftp option-value injection via concatenated argument
Expected signal: Process execution event showing ftp launched with argument '-o-p', captured by auditd EXECVE or EDR process telemetry.
- Test 3InetUtils rsh argument injection leading to shell spawning
Expected signal: Process launch event for rsh with semicolon-delimited command in arguments; potential child process event for shell spawned to execute 'id'; file creation event for /tmp/argus_injection_test.txt.
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