CVE-2019-8919 in seadroid
Summary
by MITRE
The seadroid (aka Seafile Android Client) application through 2.2.13 for Android always uses the same Initialization Vector (IV) with Cipher Block Chaining (CBC) Mode to encrypt private data, making it easier to conduct chosen-plaintext attacks or dictionary attacks.
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Analysis
by VulDB Data Team • 07/11/2023
The vulnerability identified as CVE-2019-8919 affects the seadroid application, also known as the Seafile Android Client, version 2.2.13 and earlier. This represents a critical cryptographic weakness that fundamentally undermines the security of encrypted data stored within the application. The flaw manifests in the application's implementation of symmetric encryption using Cipher Block Chaining mode, where the same Initialization Vector is consistently reused across multiple encryption operations. This behavior creates a predictable pattern that significantly weakens the cryptographic protection mechanism.
The technical flaw stems from the improper implementation of cryptographic primitives within the Android client application. When using Cipher Block Chaining mode with a fixed Initialization Vector, the encryption scheme becomes vulnerable to several well-known attack vectors. The reuse of identical IVs in CBC mode creates deterministic encryption patterns that allow attackers to perform chosen-plaintext attacks by observing how specific plaintext changes affect the ciphertext output. This vulnerability aligns with CWE-329, which specifically addresses the weakness of using predictable or repeated IVs in cryptographic operations. The cryptographic implementation violates fundamental security principles that require unique, random IVs for each encryption operation to maintain confidentiality and prevent pattern analysis.
The operational impact of this vulnerability extends beyond simple data exposure, as it enables sophisticated attack methodologies that can compromise user privacy and data integrity. Attackers can leverage the predictable encryption patterns to conduct dictionary attacks against encrypted data, potentially recovering sensitive information without requiring brute force computation of the encryption key itself. This weakness particularly affects private data stored within the Seafile Android client, including documents, files, and potentially personal information that users expect to be protected through encryption. The vulnerability creates a persistent threat vector that remains active as long as the application is installed, making it a significant concern for users who store sensitive data in the encrypted repository.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. The primary solution involves updating to a version of the seadroid application that properly implements cryptographic primitives with unique IV generation for each encryption operation. Security practitioners should also implement additional protective measures such as monitoring for unauthorized access attempts and conducting regular security assessments of mobile applications. Organizations using Seafile services should enforce policies requiring immediate updates to the latest application versions and consider implementing additional data protection layers beyond the application's native encryption. This vulnerability demonstrates the critical importance of proper cryptographic implementation in mobile applications and aligns with ATT&CK technique T1552.001, which covers unsecured credentials and data encryption weaknesses that can be exploited by adversaries to gain unauthorized access to sensitive information.