cbcvebase.
CVE-2019-12725
published 2019-07-19

CVE-2019-12725: Zeroshell 3.9.0 is prone to a remote command execution vulnerability. Specifically, this issue occurs because the web application mishandles a few HTTP…

PriorityP192critical9.8CVSS 3.0
AVNACLPRNUINSUCHIHAH
ITWEXPLOITVulnCheck KEVInitial access
Exploited in the wild
EPSS
89.85%
99.8th percentile
Zeroshell 3.9.0 is prone to a remote command execution vulnerability. Specifically, this issue occurs because the web application mishandles a few HTTP parameters. An unauthenticated attacker can exploit this issue by injecting OS commands inside the vulnerable parameters.

Affected

1 ranges
VendorProductVersion rangeFixed in
zeroshellzeroshell

Detection & IOCsextracted from sources · hover to see the quote

url/cgi-bin/kerbynet?Action=StartSessionSubmit&User='%0acat%20/etc/passwd%0a'&PW=
path/cgi-bin/kerbynet
command%27%0A%2Fetc%2Fsudo+tar+-cf+%2Fdev%2Fnull+%2Fdev%2Fnull+--checkpoint%3d1+--checkpoint-action%3dexec%3d%22<cmd>%22%0A%27
port443
snort
alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET EXPLOIT [401TRG] ZeroShell RCE Inbound (CVE-2019-12725)"; flow:established,to_server; http.uri; content:"/kerbynet?"; nocase; fast_pattern; content:"Action="; nocase; content:"Section="; nocase; reference:cve,2019-12725; reference:url,isc.sans.edu/forums/diary/Scanning+Activity+for+ZeroShell+Unauthenticated+Access/26368/; classtype:attempted-admin; sid:2030597; rev:3; metadata:attack_target Networking_Equipment, created_at 2020_07_24, cve CVE_2019_12725, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_03_07;)
  • Match HTTP GET requests to /kerbynet? URI containing both 'Action=' and 'Section=' parameters — the Emerging Threats Snort rule (sid:2030597) uses these three content matches as the core detection logic.
  • The Nuclei template confirms exploitation via a regex match on the response body for the /etc/passwd root entry, indicating successful OS command injection.
  • The Metasploit module checks for successful RCE by looking for 'uid=0(root)' in the HTTP response body after injecting the 'id' command.
  • The privilege escalation vector abuses a NOPASSWD sudo rule for /bin/tar using --checkpoint and --checkpoint-action=exec options to run arbitrary commands as root.
  • Shodan/FOFA fingerprinting: exposed Zeroshell devices can be identified by HTTP title 'zeroshell' — use for asset discovery and attack surface monitoring.
  • The x509type parameter is also an injection point (used in the Metasploit module with Action=x509view&Section=NoAuthREQ), in addition to the User parameter used in the simpler PoC.
  • ·The Metasploit module defaults to SSL (port 443). Detections scoped only to HTTP port 80 may miss exploitation attempts against HTTPS-enabled Zeroshell instances.
  • ·The Metasploit module targets x86 architecture only; payloads staged via wget cmdstager may differ for other architectures.

CVSS provenance

nvdv3.09.8CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.010.0CRITICALAV:N/AC:L/Au:N/C:C/I:C/A:C
vulncheck9.8CRITICAL
CVEs like this are exactly what “Exploited This Week” covers.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.