Ethical Hacking News
A recently disclosed vulnerability in the AWS Cloud Development Kit (CDK) exposes users to the risk of account takeover, emphasizing the importance of proactive security measures in maintaining the integrity of AWS environments.
A recent security flaw in Amazon Web Services (AWS) Cloud Development Kit (CDK) has been disclosed, highlighting the potential for account takeover risks. The vulnerability allows an attacker to gain full control over a target AWS account under specific circumstances. The issue builds upon prior findings about shadow resources in AWS and can be exploited through predictable S3 bucket names. The IAM roles created during CDK bootstrapping grant permission to upload and delete assets from associated S3 buckets, allowing an attacker to claim another user's CDK bucket. The vulnerability can be resolved by specifying a custom qualifier during bootstrapping or updating the CDK to version 2.149.0. Users are advised to maintain secure AWS account IDs, define scoped IAM policies, and avoid predictable S3 bucket names. Proactive security measures are crucial in preventing such attacks, highlighting the need for regular scanning of third-party applications and stringent security protocols.
The recent disclosure of a security flaw impacting Amazon Web Services (AWS) Cloud Development Kit (CDK) has sent shockwaves throughout the cybersecurity community, highlighting the potential for account takeover risks. This vulnerability, identified by Aqua, a cloud security firm, could have resulted in an attacker gaining administrative access to a target AWS account under specific circumstances.
According to the report shared with The Hacker News, the impact of this issue could be severe, as it allows an attacker to gain full control over a target AWS account. This is particularly concerning, given the widespread use of AWS services across various industries and organizations. The vulnerability builds upon prior findings from Aqua about shadow resources in AWS, specifically how predefined naming conventions for AWS Simple Storage Service (S3) buckets can be exploited to orchestrate Bucket Monopoly attacks.
To understand this vulnerability, it's essential to delve into the process of bootstrapping an AWS environment using the CDK. Bootstrapping involves provisioning certain AWS resources, such as an S3 bucket, Amazon Elastic Container Registry (Amazon ECR) repository, and AWS Identity and Access Management (IAM) roles. These resources are defined in an AWS CloudFormation template, which is deployed to AWS CloudFormation as a stack.
The IAM roles created during the bootstrapping process grant permission to upload and delete assets from the associated S3 bucket, as well as perform stack deployments with administrative access. The naming pattern of these IAM roles follows the structure "cdk-{Qualifier}-{Description}-{Account-ID}-{Region}", where each field is explained below:
- Qualifier: a unique nine-character string value that defaults to "hnb659fds" but can be customized during the bootstrapping phase.
- Description: resource description, such as cfn-exec-role.
- Account-ID: AWS account ID of the environment.
- Region: AWS region of the environment.
In a similar vein, the S3 bucket created during bootstrapping follows the naming pattern "cdk-{Qualifier}-assets-{Account-ID}-{Region}". Given that many users run the CDK bootstrap command without customizing the qualifier, this results in predictable S3 bucket names. With thousands of instances discovered on GitHub where the default qualifier is used, it becomes relatively simple to guess the bucket's name by finding the AWS Account ID and region to which the CDK is deployed.
This predictability opens a loophole for what's called S3 Bucket Namesquatting (or Bucket Sniping), allowing an attacker to claim another user's CDK bucket if it doesn't exist already. This could then pave the way for a partial denial-of-service (DoS) when a user attempts to bootstrap the CDK with the same account ID and region, a scenario that could be resolved by specifying a custom qualifier during bootstrapping.
A more serious consequence of this vulnerability lies in its potential to compromise sensitive data stored within S3 buckets controlled by the victim's AWS account. If the victim's CDK has permission to both read and write data from and to the attacker-controlled S3 bucket, it becomes possible for the attacker to tamper with CloudFormation templates and execute malicious actions within the victim's AWS account.
The deploy role of the CloudFormation service, which is the role CloudFormationExecutionRole in CDK, has administrative privileges within the account by default. This means that any CloudFormation template written to the attacker's S3 bucket by the victim's CDK would be deployed later with administrative privileges in the victim's account, allowing the attacker to create privileged resources.
The vulnerability was discovered and responsibly disclosed by Aqua, a cloud security firm, following responsible disclosure on June 27, 2024. The issue was addressed by the project maintainers in CDK version 2.149.0 released in July, which ensures that assets are only uploaded to buckets within the user's account, thus preventing the CDK from pushing data to buckets not owned by the account launched the bootstrapping.
However, this fix highlights the importance of proactive security measures for AWS users. If a user has initiated the CDK bootstrap process using an earlier version of CDK (v2.148.1 or earlier), they will need to update their CDK to the latest version and re-run the bootstrap command. Alternatively, users have the option of applying an IAM policy condition to the FilePublishingRole CDK role.
The findings once again call for caution regarding AWS account IDs being kept secret, defining scoped IAM policies, and avoiding predictable names for S3 buckets. Instead, generating unique hashes or random identifiers per region and incorporating them into your S3 bucket names can provide a protective measure against attackers preemptively claiming your bucket.
This vulnerability underscores the importance of staying vigilant in maintaining the security posture of AWS environments, emphasizing that user action is required to mitigate risks associated with this vulnerability. Following best practices for securing AWS resources and taking proactive measures to identify vulnerabilities are crucial in preventing such attacks.
Furthermore, recent findings highlight broader issues within software applications, as Broadcom-owned Symantec discovered several Android and iOS apps containing hardcoded and unencrypted cloud service credentials for AWS and Microsoft Azure Blob Storage, posing significant risks to user data. This highlights the need for stringent security protocols and regular scanning of third-party applications to prevent similar vulnerabilities.
In conclusion, the recent discovery of a vulnerability in the AWS Cloud Development Kit has underscored the importance of proactive measures in maintaining the security of AWS environments. By recognizing the potential risks associated with this vulnerability and taking immediate action, users can significantly reduce their exposure to account takeover risks.
Related Information:
https://thehackernews.com/2024/10/aws-cloud-development-kit-vulnerability.html
https://www.techtarget.com/searchSecurity/news/366614325/AWS-CDK-security-issue-could-lead-to-account-takeovers
https://attack.mitre.org/groups/G0143/
https://attack.mitre.org/groups/
Published: Thu Oct 24 10:08:47 2024 by llama3.2 3B Q4_K_M
