ET EXPLOIT Zyxel runCommandInShell Telnet Service Command Injection Attempt (CVE-2024-40891)

Query · suricata

flow:established,to_server;
pcre:"/^.*(?:cat|ifconfig|ping|ps|pwd|tftp|wlctl).*?(?:(?:\x3b|%3[Bb])|(?:\x0a|%0[Aa])|(?:\x60|%60)|(?:\x7c|%7[Cc])|(?:\x24|%24)|(?:\x26|%26))*?sh/";
content:"sh"; fast_pattern;
target:dest_ip;
Raw source ET EXPLOIT Zyxel runCommandInShell Telnet Service Command Injection Attempt (CVE-2024-40891) · Suricata
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Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert tcp any any -> $HOME_NET 23 (
    msg:"ET EXPLOIT Zyxel runCommandInShell Telnet Service Command Injection Attempt (CVE-2024-40891)";
    flow:established,to_server;
    pcre:"/^.*(?:cat|ifconfig|ping|ps|pwd|tftp|wlctl).*?(?:(?:\x3b|%3[Bb])|(?:\x0a|%0[Aa])|(?:\x60|%60)|(?:\x7c|%7[Cc])|(?:\x24|%24)|(?:\x26|%26))*?sh/";
    content:"sh"; fast_pattern;
    reference:cve,2024-40891;
    reference:url,vulncheck.com/blog/zyxel-telnet-vulns;
    classtype:attempted-admin;
    sid:2060323; rev:2;
    metadata:affected_product Zyxel, attack_target Networking_Equipment, tls_state plaintext, created_at 2025_02_24, cve CVE_2024_40891, deployment Perimeter, deployment Internal, performance_impact Moderate, confidence Medium, signature_severity Major, tag Exploit, tag CISA_KEV, updated_at 2025_03_03, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;
    target:dest_ip;
)

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