Performing Cloud Incident Containment Procedures

执行云事件遏制程序（Performing Cloud Incident Containment Procedures）

概述

云事件遏制需要采用与传统本地响应截然不同的云原生方法。遏制程序必须利用平台特定的控制措施，包括安全组、IAM 策略、网络 ACL 和服务级隔离，以限制受攻陷资源同时保全取证证据。2025 年 Unit 42 全球事件响应报告指出，响应云事件需要理解共享责任模型、短暂基础设施和 API 驱动的操作。有效的遏制包括凭据撤销、资源隔离、证据快照创建以及自动化响应 Playbook 执行。

AWS 遏制程序

1. 凭据攻陷遏制

# 禁用受攻陷 IAM 用户的访问密钥
aws iam update-access-key --user-name compromised-user \
  --access-key-id AKIA... --status Inactive

# 列出并禁用用户的所有访问密钥
aws iam list-access-keys --user-name compromised-user
aws iam delete-access-key --user-name compromised-user --access-key-id AKIA...

# 向受攻陷用户附加拒绝所有策略
aws iam put-user-policy --user-name compromised-user \
  --policy-name DenyAll \
  --policy-document '{
    "Version": "2012-10-17",
    "Statement": [{
      "Effect": "Deny",
      "Action": "*",
      "Resource": "*"
    }]
  }'

# 撤销 IAM 角色的所有活跃会话
aws iam put-role-policy --role-name compromised-role \
  --policy-name RevokeOldSessions \
  --policy-document '{
    "Version": "2012-10-17",
    "Statement": [{
      "Effect": "Deny",
      "Action": "*",
      "Resource": "*",
      "Condition": {
        "DateLessThan": {"aws:TokenIssueTime": "'$(date -u +%Y-%m-%dT%H:%M:%SZ)'"}
      }
    }]
  }'

# 通过更新角色信任策略使临时凭据失效
aws iam update-assume-role-policy --role-name compromised-role \
  --policy-document '{"Version":"2012-10-17","Statement":[]}'

2. EC2 实例隔离

# 创建隔离安全组（无入站、无出站）
aws ec2 create-security-group --group-name quarantine-sg \
  --description "Quarantine - No traffic allowed" --vpc-id vpc-xxxxx

# 删除隔离 SG 的所有规则（默认允许出站）
aws ec2 revoke-security-group-egress --group-id sg-quarantine \
  --ip-permissions '[{"IpProtocol":"-1","FromPort":-1,"ToPort":-1,"IpRanges":[{"CidrIp":"0.0.0.0/0"}]}]'

# 遏制前先创建取证快照
aws ec2 create-snapshot --volume-id vol-xxxxx \
  --description "Forensic snapshot - IR Case 2025-001" \
  --tag-specifications 'ResourceType=snapshot,Tags=[{Key=IR-Case,Value=2025-001}]'

# 将隔离安全组应用到受攻陷实例
aws ec2 modify-instance-attribute --instance-id i-xxxxx \
  --groups sg-quarantine

# 将实例标记为已攻陷
aws ec2 create-tags --resources i-xxxxx \
  --tags Key=IR-Status,Value=Contained Key=IR-Case,Value=2025-001

# 采集内存（如果 SSM Agent 可用）
aws ssm send-command --instance-ids i-xxxxx \
  --document-name "AWS-RunShellScript" \
  --parameters 'commands=["dd if=/dev/mem of=/tmp/memory.dump bs=1M"]'

3. S3 存储桶遏制

# 阻断所有公共访问
aws s3api put-public-access-block --bucket compromised-bucket \
  --public-access-block-configuration \
  BlockPublicAcls=true,IgnorePublicAcls=true,BlockPublicPolicy=true,RestrictPublicBuckets=true

# 应用拒绝策略到存储桶
aws s3api put-bucket-policy --bucket compromised-bucket \
  --policy '{
    "Version": "2012-10-17",
    "Statement": [{
      "Sid": "DenyAllExceptForensics",
      "Effect": "Deny",
      "NotPrincipal": {"AWS": "arn:aws:iam::ACCOUNT:role/IR-Forensics"},
      "Action": "s3:*",
      "Resource": ["arn:aws:s3:::compromised-bucket","arn:aws:s3:::compromised-bucket/*"]
    }]
  }'

# 启用版本控制以保全证据
aws s3api put-bucket-versioning --bucket compromised-bucket \
  --versioning-configuration Status=Enabled

# 为证据保全启用对象锁定
aws s3api put-object-lock-configuration --bucket evidence-bucket \
  --object-lock-configuration '{
    "ObjectLockEnabled": "Enabled",
    "Rule": {"DefaultRetention": {"Mode": "COMPLIANCE", "Days": 365}}
  }'

4. Lambda 函数遏制

# 将预留并发设置为 0（停止所有调用）
aws lambda put-function-concurrency --function-name compromised-function \
  --reserved-concurrent-executions 0

# 删除所有事件源映射
aws lambda list-event-source-mappings --function-name compromised-function
aws lambda delete-event-source-mapping --uuid mapping-uuid

Azure 遏制程序

1. 身份遏制

# 撤销所有用户会话
Revoke-AzureADUserAllRefreshToken -ObjectId "user-object-id"

# 禁用用户账号
Set-AzureADUser -ObjectId "user-object-id" -AccountEnabled $false

# 重置用户密码
Set-AzureADUserPassword -ObjectId "user-object-id" -Password (
  ConvertTo-SecureString "TempP@ss!" -AsPlainText -Force
) -ForceChangePasswordNextLogin $true

# 通过条件访问阻断登录（紧急策略）
# 创建策略阻止用户访问所有云应用

# 撤销 Azure AD 应用授权
Remove-AzureADServiceAppRoleAssignment -ObjectId "sp-object-id" \
  -AppRoleAssignmentId "assignment-id"

2. VM 隔离

# 创建带拒绝所有规则的网络安全组
$nsg = New-AzNetworkSecurityGroup -ResourceGroupName "rg" -Location "eastus" `
  -Name "quarantine-nsg" `
  -SecurityRules @(
    New-AzNetworkSecurityRuleConfig -Name "DenyAllInbound" -Protocol * `
      -Direction Inbound -Priority 100 -SourceAddressPrefix * `
      -SourcePortRange * -DestinationAddressPrefix * `
      -DestinationPortRange * -Access Deny,
    New-AzNetworkSecurityRuleConfig -Name "DenyAllOutbound" -Protocol * `
      -Direction Outbound -Priority 100 -SourceAddressPrefix * `
      -SourcePortRange * -DestinationAddressPrefix * `
      -DestinationPortRange * -Access Deny
  )

# 创建取证磁盘快照
$vm = Get-AzVM -ResourceGroupName "rg" -Name "compromised-vm"
$snapshotConfig = New-AzSnapshotConfig -SourceUri $vm.StorageProfile.OsDisk.ManagedDisk.Id `
  -Location "eastus" -CreateOption Copy
New-AzSnapshot -ResourceGroupName "rg" -SnapshotName "forensic-snap" -Snapshot $snapshotConfig

# 将隔离 NSG 应用到 VM NIC
$nic = Get-AzNetworkInterface -ResourceGroupName "rg" -Name "compromised-nic"
$nic.NetworkSecurityGroup = $nsg
Set-AzNetworkInterface -NetworkInterface $nic

3. 存储账号遏制

# 删除网络访问
Update-AzStorageAccountNetworkRuleSet -ResourceGroupName "rg" `
  -Name "storageaccount" -DefaultAction Deny

# 重新生成访问密钥
New-AzStorageAccountKey -ResourceGroupName "rg" -Name "storageaccount" -KeyName key1
New-AzStorageAccountKey -ResourceGroupName "rg" -Name "storageaccount" -KeyName key2

# 通过轮换密钥撤销所有 SAS 令牌
# 为证据保全启用不可变性

GCP 遏制程序

1. IAM 遏制

# 删除受攻陷服务账号的所有 IAM 绑定
gcloud projects get-iam-policy PROJECT_ID --format=json > policy.json
# 编辑 policy.json 删除受攻陷账号的绑定
gcloud projects set-iam-policy PROJECT_ID policy.json

# 禁用服务账号
gcloud iam service-accounts disable SA_EMAIL

# 删除服务账号密钥
gcloud iam service-accounts keys list --iam-account SA_EMAIL
gcloud iam service-accounts keys delete KEY_ID --iam-account SA_EMAIL

2. 计算实例隔离

# 创建取证快照
gcloud compute disks snapshot compromised-disk \
  --snapshot-names forensic-snap-$(date +%Y%m%d) \
  --zone us-central1-a

# 应用防火墙规则拒绝所有流量
gcloud compute firewall-rules create quarantine-deny-all \
  --network default --action DENY --rules all \
  --target-tags quarantine --priority 0

# 标记受攻陷实例
gcloud compute instances add-tags compromised-instance \
  --tags quarantine --zone us-central1-a

# 删除外部 IP
gcloud compute instances delete-access-config compromised-instance \
  --access-config-name "External NAT" --zone us-central1-a

证据保全最佳实践

1. 遏制前始终创建快照 - 在网络隔离前创建磁盘/卷快照
2. 保全 CloudTrail/活动日志 - 将日志复制到写保护存储
3. 记录所有操作 - 为每个遏制步骤添加时间戳
4. 使用紧急访问程序 - 为 IR 团队预先建立紧急访问
5. 维护取证证据链 - 对所有证据产物计算哈希

MITRE ATT&CK 云技术

参考资料

• Sygnia：云事件响应最佳实践
• Unit 42：响应云事件
• Wiz：云事件响应检查清单
• Microsoft 云安全基准 - IR