nuclei-templates/code/linux/audit/sendmail-postfix-execution-restrictions.yaml

id: sendmail-postfix-execution-restrictions

info:
  name: Sendmail/Postfix Execution Restrictions Misconfigured
  author: songyaeji
  severity: medium
  description: |
    General users were not restricted from executing Sendmail with the q option, and the Postfix binary lacked proper permission controls.This misconfiguration allowed unauthorized users to manipulate the mail queue or disrupt mail delivery.
  reference:
    - https://isms.kisa.or.kr
  tags: local,linux,audit,sendmail,postfix,compliance

self-contained: true

code:
  - engine:
      - bash
    source: |
      if ! grep -qi 'restrictqrun' /etc/mail/sendmail.cf 2>/dev/null; then
        echo "[VULNERABLE] sendmail.cf missing 'restrictqrun'"
      else
        echo "[SAFE] restrictqrun option is set in sendmail.cf"
      fi

  - engine:
      - bash
    source: |
      if [ -x /usr/sbin/postfix ]; then
        PERM="$(stat -c '%A' /usr/sbin/postfix 2>/dev/null || echo '')"
        if [ "$PERM" != "-rwxr-x---" ]; then
          echo "[VULNERABLE] /usr/sbin/postfix permission is '$PERM' (expected -rwxr-x---)"
        else
          echo "[SAFE] postfix binary permission is correct"
        fi
      fi

  - engine:
      - bash
    source: |
      if getent group postfix >/dev/null 2>&1; then
        MEMBERS="$(getent group postfix | awk -F ':' '{print $4}')"
        echo "$MEMBERS" | grep -qw root || echo "[VULNERABLE] 'root' not in 'postfix' group"
      fi

    matchers:
      - type: word
        name: restrictqrun
        part: code_1_response
        words:
          - "[VULNERABLE]"

      - type: word
        name: postfix-permission
        part: code_2_response
        words:
          - "[VULNERABLE]"

      - type: word
        name: postfix-group
        part: code_3_response
        words:
          - "[VULNERABLE]"
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