本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# Image Builder 的安全最佳實務
<a name="security-best-practices"></a>

EC2 Image Builder 提供多種安全功能，供您在開發和實作自己的安全政策時加以考量。以下最佳實務為一般準則，並不代表完整的安全解決方案。這些最佳實務可能不適用或無法滿足您的環境需求，因此請將其視為實用建議就好，而不要當作是指示。
+ 請勿在映像建置器配方中使用過於寬鬆的安全群組。
+ 請勿與您不信任的帳戶共用映像。
+ 請勿公開具有私有或敏感資料的映像。
+ 在映像建置期間套用所有可用的 Windows 或 Linux 安全修補程式。
+ 定期將受管 AMI 更新套用至您的 macOS 配方，並建立新的映像以啟動具有最新安全修補程式的執行個體。

我們強烈建議您測試映像，以驗證安全狀態和適用的安全合規等級。[Amazon Inspector](https://aws.amazon.com/inspector/) 等解決方案可協助驗證映像的安全性和合規狀態。

**適用於映像建置器管道的 IMDSv2**  
當您的 Image Builder 管道執行時，它會傳送 HTTP 請求，以啟動 Image Builder 用來建置和測試映像的 EC2 執行個體。若要設定管道用於啟動請求的 IMDS 版本，請在 Image Builder 基礎設施組態執行個體中繼資料設定中設定 `httpTokens` 參數。

**注意**  
我們建議您將映像建置器從管道建置啟動的所有 EC2 執行個體設定為使用 IMDSv2，以便執行個體中繼資料擷取請求需要簽章權杖標頭。

如需映像建置器基礎設施組態的詳細資訊，請參閱[管理映像建置器基礎設施組態](manage-infra-config.md)。如需 Linux 映像的 EC2 執行個體中繼資料選項的詳細資訊，請參閱《Amazon EC2 使用者指南》中的[設定執行個體中繼資料選項](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-options.html)。對於 Windows 映像，請參閱《Amazon EC2 使用者指南》中的[設定執行個體中繼資料選項](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-options.html)。

## 必要的建置後清除
<a name="post-build-cleanup"></a>

Image Builder 完成自訂映像的所有建置步驟後，Image Builder 會準備建置執行個體以進行測試和建立映像。關閉建置執行個體以建立快照之前，Image Builder 會執行下列清除作業，以確保您映像的安全性：

------
#### [ Linux ]

Image Builder 管道會執行清除指令碼，以協助確保最終映像遵循安全最佳實務，並移除任何不應傳遞至快照的建置成品或設定。不過，您可以略過指令碼的區段，或完全覆寫使用者資料。因此，Image Builder 管道產生的映像不一定符合任何特定的法規條件。

當管道完成建置和測試階段時，Image Builder 會在建立輸出映像之前自動執行下列清除指令碼。

**重要**  
如果您覆寫配方中的**使用者資料**，則指令碼不會執行。在這種情況下，請確定您在使用者資料中包含一個命令，該命令會建立名為 的空白檔案`perform_cleanup`。Image Builder 會偵測此檔案，並在建立新映像之前執行清除指令碼。

```
#!/bin/bash
if [[ ! -f {{workingDirectory}}/perform_cleanup ]]; then
    echo "Skipping cleanup"
    exit 0
else
    sudo rm -f {{workingDirectory}}/perform_cleanup
fi

function cleanup() {
    FILES=("$@")
    for FILE in "${FILES[@]}"; do
        if [[ -f "$FILE" ]]; then
            echo "Deleting $FILE";
            sudo shred -zuf $FILE;
        fi;
        if [[ -f $FILE ]]; then
            echo "Failed to delete '$FILE'. Failing."
            exit 1
        fi;
    done
};


# Clean up for cloud-init files
CLOUD_INIT_FILES=(
    "/etc/sudoers.d/90-cloud-init-users"
    "/etc/locale.conf"
    "/var/log/cloud-init.log"
    "/var/log/cloud-init-output.log"
)
if [[ -f {{workingDirectory}}/skip_cleanup_cloudinit_files ]]; then
    echo "Skipping cleanup of cloud init files"
else
    echo "Cleaning up cloud init files"
    cleanup "${CLOUD_INIT_FILES[@]}"
    if [[ $( sudo find /var/lib/cloud -type f | sudo wc -l ) -gt 0 ]]; then
        echo "Deleting files within /var/lib/cloud/*"
        sudo find /var/lib/cloud -type f -exec shred -zuf {} \;
    fi;

    if [[ $( sudo ls /var/lib/cloud | sudo wc -l ) -gt 0 ]]; then
        echo "Deleting /var/lib/cloud/*"
        sudo rm -rf /var/lib/cloud/* || true
    fi;
fi;


# Clean up for temporary instance files
INSTANCE_FILES=(
    "/etc/.updated"
    "/etc/aliases.db"
    "/etc/hostname"
    "/var/lib/misc/postfix.aliasesdb-stamp"
    "/var/lib/postfix/master.lock"
    "/var/spool/postfix/pid/master.pid"
    "/var/.updated"
    "/var/cache/yum/x86_64/2/.gpgkeyschecked.yum"
)
if [[ -f {{workingDirectory}}/skip_cleanup_instance_files ]]; then
    echo "Skipping cleanup of instance files"
else
    echo "Cleaning up instance files"
    cleanup "${INSTANCE_FILES[@]}"
fi;


# Clean up for ssh files
SSH_FILES=(
    "/etc/ssh/ssh_host_rsa_key"
    "/etc/ssh/ssh_host_rsa_key.pub"
    "/etc/ssh/ssh_host_ecdsa_key"
    "/etc/ssh/ssh_host_ecdsa_key.pub"
    "/etc/ssh/ssh_host_ed25519_key"
    "/etc/ssh/ssh_host_ed25519_key.pub"
    "/root/.ssh/authorized_keys"
)
if [[ -f {{workingDirectory}}/skip_cleanup_ssh_files ]]; then
    echo "Skipping cleanup of ssh files"
else
    echo "Cleaning up ssh files"
    cleanup "${SSH_FILES[@]}"
    USERS=$(ls /home/)
    for user in $USERS; do
        echo Deleting /home/"$user"/.ssh/authorized_keys;
        sudo find /home/"$user"/.ssh/authorized_keys -type f -exec shred -zuf {} \;
    done
    for user in $USERS; do
        if [[ -f /home/"$user"/.ssh/authorized_keys ]]; then
            echo Failed to delete /home/"$user"/.ssh/authorized_keys;
            exit 1
        fi;
    done;
fi;


# Clean up for instance log files
INSTANCE_LOG_FILES=(
    "/var/log/audit/audit.log"
    "/var/log/boot.log"
    "/var/log/dmesg"
    "/var/log/cron"
)
if [[ -f {{workingDirectory}}/skip_cleanup_instance_log_files ]]; then
    echo "Skipping cleanup of instance log files"
else
    echo "Cleaning up instance log files"
    cleanup "${INSTANCE_LOG_FILES[@]}"
fi;

# Clean up for TOE files
if [[ -f {{workingDirectory}}/skip_cleanup_toe_files ]]; then
    echo "Skipping cleanup of TOE files"
else
    echo "Cleaning TOE files"
    if [[ $( sudo find {{workingDirectory}}/TOE_* -type f | sudo wc -l) -gt 0 ]]; then
        echo "Deleting files within {{workingDirectory}}/TOE_*"
        sudo find {{workingDirectory}}/TOE_* -type f -exec shred -zuf {} \;
    fi
    if [[ $( sudo find {{workingDirectory}}/TOE_* -type f | sudo wc -l) -gt 0 ]]; then
        echo "Failed to delete {{workingDirectory}}/TOE_*"
        exit 1
    fi
    if [[ $( sudo find {{workingDirectory}}/TOE_* -type d | sudo wc -l) -gt 0 ]]; then
        echo "Deleting {{workingDirectory}}/TOE_*"
        sudo rm -rf {{workingDirectory}}/TOE_*
    fi
    if [[ $( sudo find {{workingDirectory}}/TOE_* -type d | sudo wc -l) -gt 0 ]]; then
        echo "Failed to delete {{workingDirectory}}/TOE_*"
        exit 1
    fi
fi

# Clean up for ssm log files
if [[ -f {{workingDirectory}}/skip_cleanup_ssm_log_files ]]; then
    echo "Skipping cleanup of ssm log files"
else
    echo "Cleaning up ssm log files"
    if [[ $( sudo find /var/log/amazon/ssm -type f | sudo wc -l) -gt 0 ]]; then
        echo "Deleting files within /var/log/amazon/ssm/*"
        sudo find /var/log/amazon/ssm -type f -exec shred -zuf {} \;
    fi
    if [[ $( sudo find /var/log/amazon/ssm -type f | sudo wc -l) -gt 0 ]]; then
        echo "Failed to delete /var/log/amazon/ssm"
        exit 1
    fi
    if [[ -d "/var/log/amazon/ssm" ]]; then
        echo "Deleting /var/log/amazon/ssm/*"
        sudo rm -rf /var/log/amazon/ssm
    fi
    if [[ -d "/var/log/amazon/ssm" ]]; then
        echo "Failed to delete /var/log/amazon/ssm"
        exit 1
    fi
fi


if [[ $( sudo find /var/log/sa/sa* -type f | sudo wc -l ) -gt 0 ]]; then
    echo "Deleting /var/log/sa/sa*"
    sudo shred -zuf /var/log/sa/sa*
fi
if [[ $( sudo find /var/log/sa/sa* -type f | sudo wc -l ) -gt 0 ]]; then
    echo "Failed to delete /var/log/sa/sa*"
    exit 1
fi

if [[ $( sudo find /var/lib/dhclient/dhclient*.lease -type f | sudo wc -l ) -gt 0 ]]; then
        echo "Deleting /var/lib/dhclient/dhclient*.lease"
        sudo shred -zuf /var/lib/dhclient/dhclient*.lease
fi
if [[ $( sudo find /var/lib/dhclient/dhclient*.lease -type f | sudo wc -l ) -gt 0 ]]; then
        echo "Failed to delete /var/lib/dhclient/dhclient*.lease"
        exit 1
fi

if [[ $( sudo find /var/tmp -type f | sudo wc -l) -gt 0 ]]; then
        echo "Deleting files within /var/tmp/*"
        sudo find /var/tmp -type f -exec shred -zuf {} \;
fi
if [[ $( sudo find /var/tmp -type f | sudo wc -l) -gt 0 ]]; then
        echo "Failed to delete /var/tmp"
        exit 1
fi
if [[ $( sudo ls /var/tmp | sudo wc -l ) -gt 0 ]]; then
        echo "Deleting /var/tmp/*"
        sudo rm -rf /var/tmp/*
fi

# Shredding is not guaranteed to work well on rolling logs

if [[ -f "/var/lib/rsyslog/imjournal.state" ]]; then
        echo "Deleting /var/lib/rsyslog/imjournal.state"
        sudo shred -zuf /var/lib/rsyslog/imjournal.state
        sudo rm -f /var/lib/rsyslog/imjournal.state
fi

if [[ $( sudo ls /var/log/journal/ | sudo wc -l ) -gt 0 ]]; then
        echo "Deleting /var/log/journal/*"
        sudo find /var/log/journal/ -type f -exec shred -zuf {} \;
        sudo rm -rf /var/log/journal/*
fi

sudo touch /etc/machine-id
```

------
#### [ Windows ]

在映像建置器管道自訂 Windows 映像之後，它會執行 Microsoft [Sysprep](https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/sysprep--generalize--a-windows-installation?view=windows-11) 公用程式。這些動作遵循[AWS 強化和清理映像的最佳實務](https://aws.amazon.com/articles/public-ami-publishing-hardening-and-clean-up-requirements/)。

------
#### [ macOS ]

Image Builder 管道會執行清除指令碼，以協助確保最終映像遵循安全最佳實務，並移除任何不應傳遞至快照的建置成品或設定。不過，您可以略過指令碼的區段，或完全覆寫使用者資料。因此，Image Builder 管道產生的映像不一定符合任何特定的法規條件。

當管道完成建置和測試階段時，Image Builder 會在建立輸出映像之前自動執行下列清除指令碼。

**重要**  
如果您覆寫配方中的**使用者資料**，則指令碼不會執行。在這種情況下，請確定您在使用者資料中包含一個命令，該命令會建立名為 的空白檔案`perform_cleanup`。Image Builder 會偵測此檔案，並在建立新映像之前執行清除指令碼。

```
#!/bin/bash
if [[ ! -f {{workingDirectory}}/perform_cleanup ]]; then
  echo "Skipping cleanup"
  exit 0
else
  sudo rm -f {{workingDirectory}}/perform_cleanup
fi

function cleanup() {
  FILES=("$@")
  for FILE in "${FILES[@]}"; do
      if [[ -f "$FILE" ]]; then
          echo "Deleting $FILE";
          sudo rm -f $FILE;
      fi;
      if [[ -f $FILE ]]; then
          echo "Failed to delete '$FILE'. Failing."
          exit 1
      fi;
  done
};

# Clean up for cloud-init files
CLOUD_INIT_FILES=(
  "/etc/sudoers.d/90-cloud-init-users"
  "/etc/locale.conf"
  "/var/log/cloud-init.log"
  "/var/log/cloud-init-output.log"
)
if [[ -f {{workingDirectory}}/skip_cleanup_cloudinit_files ]]; then
  echo "Skipping cleanup of cloud init files"
else
  echo "Cleaning up cloud init files"
  cleanup "${CLOUD_INIT_FILES[@]}"
  if [[ $( sudo find /var/lib/cloud -type f | sudo wc -l ) -gt 0 ]]; then
      echo "Deleting files within /var/lib/cloud/*"
      sudo find /var/lib/cloud -type f -exec rm -f {} \;
  fi;

  if [[ $( sudo ls /var/lib/cloud | sudo wc -l ) -gt 0 ]]; then
      echo "Deleting /var/lib/cloud/*"
      sudo rm -rf /var/lib/cloud/* || true
  fi;
fi;


# Clean up for temporary instance files
INSTANCE_FILES=(
  "/etc/.updated"
  "/etc/aliases.db"
  "/etc/hostname"
  "/var/lib/misc/postfix.aliasesdb-stamp"
  "/var/lib/postfix/master.lock"
  "/var/spool/postfix/pid/master.pid"
  "/var/.updated"
  "/var/cache/yum/x86_64/2/.gpgkeyschecked.yum"
)
if [[ -f {{workingDirectory}}/skip_cleanup_instance_files ]]; then
  echo "Skipping cleanup of instance files"
else
  echo "Cleaning up instance files"
  cleanup "${INSTANCE_FILES[@]}"
fi;


# Clean up for ssh files
SSH_FILES=(
  "/etc/ssh/ssh_host_rsa_key"
  "/etc/ssh/ssh_host_rsa_key.pub"
  "/etc/ssh/ssh_host_ecdsa_key"
  "/etc/ssh/ssh_host_ecdsa_key.pub"
  "/etc/ssh/ssh_host_ed25519_key"
  "/etc/ssh/ssh_host_ed25519_key.pub"
  "/root/.ssh/authorized_keys"
)
if [[ -f {{workingDirectory}}/skip_cleanup_ssh_files ]]; then
  echo "Skipping cleanup of ssh files"
else
  echo "Cleaning up ssh files"
  cleanup "${SSH_FILES[@]}"
  USERS=$(ls /home/)
  for user in $USERS; do
      echo Deleting /home/"$user"/.ssh/authorized_keys;
      sudo find /home/"$user"/.ssh/authorized_keys -type f -exec rm -f {} \;
  done
  for user in $USERS; do
      if [[ -f /home/"$user"/.ssh/authorized_keys ]]; then
          echo Failed to delete /home/"$user"/.ssh/authorized_keys;
          exit 1
      fi;
  done;
fi;


# Clean up for instance log files
INSTANCE_LOG_FILES=(
  "/var/log/audit/audit.log"
  "/var/log/boot.log"
  "/var/log/dmesg"
  "/var/log/cron"
  "/var/log/amazon/ec2/ec2-macos-init.log"
  "/var/log/amazon/ec2/ena-ethernet.log"
  "/var/log/amazon/ec2/system-monitoring.log"
)
if [[ -f {{workingDirectory}}/skip_cleanup_instance_log_files ]]; then
  echo "Skipping cleanup of instance log files"
else
  echo "Cleaning up instance log files"
  cleanup "${INSTANCE_LOG_FILES[@]}"
fi;

# Clean up for TOE files
if [[ -f {{workingDirectory}}/skip_cleanup_toe_files ]]; then
  echo "Skipping cleanup of TOE files"
else
  echo "Cleaning TOE files"
  if [[ $( sudo find {{workingDirectory}}/TOE_* -type f | sudo wc -l) -gt 0 ]]; then
      echo "Deleting files within {{workingDirectory}}/TOE_*"
      sudo find {{workingDirectory}}/TOE_* -type f -exec rm -f {} \;
  fi
  if [[ $( sudo find {{workingDirectory}}/TOE_* -type f | sudo wc -l) -gt 0 ]]; then
      echo "Failed to delete {{workingDirectory}}/TOE_*"
      exit 1
  fi
  if [[ $( sudo find {{workingDirectory}}/TOE_* -type d | sudo wc -l) -gt 0 ]]; then
      echo "Deleting {{workingDirectory}}/TOE_*"
      sudo rm -rf {{workingDirectory}}/TOE_*
  fi
  if [[ $( sudo find {{workingDirectory}}/TOE_* -type d | sudo wc -l) -gt 0 ]]; then
      echo "Failed to delete {{workingDirectory}}/TOE_*"
      exit 1
  fi
fi

# Clean up for ssm log files
if [[ -f {{workingDirectory}}/skip_cleanup_ssm_log_files ]]; then
  echo "Skipping cleanup of ssm log files"
else
  echo "Cleaning up ssm log files"
  if [[ $( sudo find /var/log/amazon/ssm -type f | sudo wc -l) -gt 0 ]]; then
      echo "Deleting files within /var/log/amazon/ssm/*"
      sudo find /var/log/amazon/ssm -type f -exec rm -f {} \;
  fi
  if [[ $( sudo find /var/log/amazon/ssm -type f | sudo wc -l) -gt 0 ]]; then
      echo "Failed to delete /var/log/amazon/ssm"
      exit 1
  fi
  if [[ -d "/var/log/amazon/ssm" ]]; then
      echo "Deleting /var/log/amazon/ssm/*"
      sudo rm -rf /var/log/amazon/ssm
  fi
  if [[ -d "/var/log/amazon/ssm" ]]; then
      echo "Failed to delete /var/log/amazon/ssm"
      exit 1
  fi
fi


if [[ $( sudo find /var/log/sa/sa* -type f | sudo wc -l ) -gt 0 ]]; then
  echo "Deleting /var/log/sa/sa*"
  sudo rm -f /var/log/sa/sa*
fi
if [[ $( sudo find /var/log/sa/sa* -type f | sudo wc -l ) -gt 0 ]]; then
  echo "Failed to delete /var/log/sa/sa*"
  exit 1
fi

if [[ $( sudo find /var/lib/dhclient/dhclient*.lease -type f | sudo wc -l ) -gt 0 ]]; then
      echo "Deleting /var/lib/dhclient/dhclient*.lease"
      sudo rm -f /var/lib/dhclient/dhclient*.lease
fi
if [[ $( sudo find /var/lib/dhclient/dhclient*.lease -type f | sudo wc -l ) -gt 0 ]]; then
      echo "Failed to delete /var/lib/dhclient/dhclient*.lease"
      exit 1
fi

if [[ $( sudo find /var/tmp -type f | sudo wc -l) -gt 0 ]]; then
      echo "Deleting files within /var/tmp/*"
      sudo find /var/tmp -type f -exec rm -f {} \;
fi
if [[ $( sudo find /var/tmp -type f | sudo wc -l) -gt 0 ]]; then
      echo "Failed to delete /var/tmp"
      exit 1
fi
if [[ $( sudo ls /var/tmp | sudo wc -l ) -gt 0 ]]; then
      echo "Deleting /var/tmp/*"
      sudo rm -rf /var/tmp/*
fi

# Shredding is not guaranteed to work well on rolling logs

if [[ -f "/var/lib/rsyslog/imjournal.state" ]]; then
      echo "Deleting /var/lib/rsyslog/imjournal.state"
      sudo rm -f /var/lib/rsyslog/imjournal.state
      sudo rm -f /var/lib/rsyslog/imjournal.state
fi

if [[ $( sudo ls /var/log/journal/ | sudo wc -l ) -gt 0 ]]; then
      echo "Deleting /var/log/journal/*"
      sudo find /var/log/journal/ -type f -exec rm -f {} \;
      sudo rm -rf /var/log/journal/*
fi

sudo touch /etc/machine-id
```

------

## 覆寫 Linux 清除指令碼
<a name="override-linux-cleanup-script"></a>

Image Builder 會建立預設安全的映像，並遵循我們的安全最佳實務。不過，有些更進階的使用案例可能會要求您略過內建清除指令碼的一或多個區段。如果您需要略過一些清除，強烈建議您測試輸出 AMI，以確保映像的安全性。

**重要**  
略過清除指令碼中的區段可能會導致敏感資訊，例如擁有者帳戶詳細資訊或 SSH 金鑰包含在最終映像中，以及從該映像啟動的任何執行個體中。您也可能會在不同的可用區域、區域或帳戶中遇到啟動問題。

下表概述清除指令碼的區段、該區段中已刪除的檔案，以及可用來標記 Image Builder 應略過之區段的檔案名稱。若要略過清除指令碼的特定區段，您可以使用[CreateFile](toe-action-modules.md#action-modules-createfile)元件動作模組或使用者資料中的命令 （如果覆寫），以**略過區段檔案名稱欄中指定的名稱建立空白檔案**。

**注意**  
您為略過清除指令碼一節而建立的檔案不應包含副檔名。例如，如果您想要略過指令碼的 `CLOUD_INIT_FILES`區段，但建立名為 的檔案`skip_cleanup_cloudinit_files.txt`，Image Builder 將無法辨識略過檔案。


**Input**  

| 清除區段 | 檔案已移除 | 略過區段檔案名稱 | 
| --- | --- | --- | 
| `CLOUD_INIT_FILES` | `/etc/sudoers.d/90-cloud-init-users` `/etc/locale.conf` `/var/log/cloud-init.log` `/var/log/cloud-init-output.log`  | `skip_cleanup_cloudinit_files` | 
| `INSTANCE_FILES` | `/etc/.updated` `/etc/aliases.db` `/etc/hostname` `/var/lib/misc/postfix.aliasesdb-stamp` `/var/lib/postfix/master.lock` `/var/spool/postfix/pid/master.pid` `/var/.updated` `/var/cache/yum/x86_64/2/.gpgkeyschecked.yum`  | `skip_cleanup_instance_files` | 
| `SSH_FILES` | `/etc/ssh/ssh_host_rsa_key` `/etc/ssh/ssh_host_rsa_key.pub` `/etc/ssh/ssh_host_ecdsa_key` `/etc/ssh/ssh_host_ecdsa_key.pub` `/etc/ssh/ssh_host_ed25519_key` `/etc/ssh/ssh_host_ed25519_key.pub` `/root/.ssh/authorized_keys` `/home/<all users>/.ssh/authorized_keys;`  | `skip_cleanup_ssh_files` | 
| `INSTANCE_LOG_FILES` | `/var/log/audit/audit.log` `/var/log/boot.log` `/var/log/dmesg` `/var/log/cron`  | `skip_cleanup_instance_log_files` | 
| `TOE_FILES` | `{{workingDirectory}}/TOE_*` | `skip_cleanup_toe_files` | 
| `SSM_LOG_FILES` | `/var/log/amazon/ssm/*` | `skip_cleanup_ssm_log_files` |