CVE-2018-19981 in AWS SDK
Summary
by MITRE
Amazon AWS SDK <=2.8.5 for Android uses Android SharedPreferences to store plain text AWS STS Temporary Credentials retrieved by AWS Cognito Identity Service. An attacker can use these credentials to create authenticated and/or authorized requests. Note that the attacker must have "root" privilege access to the Android filesystem in order to exploit this vulnerability (i.e. the device has been compromised, such as disabling or bypassing Android's fundamental security mechanisms).
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Analysis
by VulDB Data Team • 08/25/2023
The vulnerability described in CVE-2018-19981 represents a critical security flaw in Amazon AWS SDK versions 2.8.5 and earlier for Android platforms. This issue stems from the improper handling of temporary security credentials within the mobile application environment, specifically leveraging Android's SharedPreferences mechanism to store sensitive authentication data in plain text format. The AWS SDK component interacts with AWS Cognito Identity Service to retrieve temporary credentials, which are then persisted locally on the device without adequate encryption or protection measures. This design choice creates a significant attack surface that can be exploited by malicious actors who have already compromised the device's security posture.
The technical implementation of this vulnerability involves the Android SharedPreferences API, which provides a simple mechanism for storing key-value pairs of primitive data types. When the AWS SDK retrieves temporary credentials from the Cognito Identity Service, it stores these credentials in SharedPreferences without any encryption or obfuscation. The SharedPreferences mechanism, while convenient for application data storage, does not provide built-in encryption for the stored data. This creates a scenario where sensitive information such as access keys, secret keys, and session tokens are stored in plaintext within the application's private storage directory. The vulnerability becomes exploitable when an attacker gains root-level access to the Android device, which would allow them to directly read the SharedPreferences files and extract the stored credentials.
The operational impact of this vulnerability extends beyond simple credential theft, as the compromised credentials can be used to establish authenticated sessions with AWS services. Once an attacker has access to these temporary credentials, they can perform authorized operations against the associated AWS account, potentially leading to data exfiltration, service disruption, or unauthorized resource consumption. The attack vector requires the device to be compromised at the root level, which aligns with the ATT&CK framework's technique T1068 for bypassing system defenses. This requirement for root access indicates that the vulnerability is not exploitable through network-based attacks but rather through physical compromise or successful exploitation of other vulnerabilities that lead to device root access. The attack scenario typically involves adversaries who have already gained control over the device through techniques such as jailbreaking, rooting, or exploiting other device-level vulnerabilities.
The security implications of this vulnerability are particularly severe given that AWS STS temporary credentials typically have broad permissions within the associated account, especially when used in conjunction with Cognito Identity pools. These credentials can potentially provide access to various AWS services and resources, including S3 buckets, DynamoDB tables, and other cloud infrastructure components. The vulnerability classification aligns with CWE-312, which addresses the exposure of sensitive information through improper data handling. Organizations using AWS SDK for Android must consider that this vulnerability represents a failure in secure credential management practices, particularly in mobile environments where physical security controls are paramount. The lack of proper credential encryption and secure storage mechanisms makes this vulnerability particularly dangerous in environments where mobile devices may be lost, stolen, or compromised through various attack vectors.
Mitigation strategies for this vulnerability should focus on implementing proper credential storage mechanisms that protect sensitive data even when device security is compromised. The recommended approach involves upgrading to AWS SDK versions that implement secure credential storage practices, such as using Android Keystore system for credential encryption or implementing custom encryption mechanisms for storing sensitive data. Organizations should also consider implementing additional security controls such as credential rotation, monitoring for unauthorized access attempts, and implementing device management policies that enforce secure configuration practices. The solution should align with industry best practices outlined in NIST SP 800-53 for mobile device security and should address the specific requirements for credential protection in mobile environments. Regular security assessments and penetration testing should be conducted to identify potential attack vectors that could lead to device compromise and subsequent credential exposure.