CVE-2020-0259 in Android
Summary
by MITRE
In android_verity_ctr of dm-android-verity.c, there is a possible way to modify a dm-verity protected filesystem due to improperly used crypto. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-157941353References: N/A
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Analysis
by VulDB Data Team • 08/12/2020
The vulnerability identified as CVE-2020-0259 resides within the android_verity_ctr function of the dm-android-verity.c file in the Android kernel, representing a critical security flaw that undermines the integrity protection mechanisms designed to safeguard filesystems. This issue specifically affects the Device Mapper (dm-verity) implementation which is responsible for verifying the integrity of filesystems by using cryptographic checksums to detect any unauthorized modifications. The vulnerability stems from improper handling of cryptographic operations within the verification process, creating a potential pathway for malicious actors to bypass the protective measures that should prevent unauthorized filesystem alterations.
The technical flaw manifests through the improper usage of cryptographic functions during the verification process, where the system fails to properly validate the integrity of the cryptographic operations being performed. This weakness allows an attacker with local access to potentially modify a dm-verity protected filesystem without requiring any additional privileges or user interaction for exploitation. The vulnerability specifically targets the counter mode implementation within the Android verity framework, which is designed to provide authenticated encryption for protecting the integrity of filesystem data. When the cryptographic operations are not properly enforced, the system may accept modified data as valid, effectively neutralizing the security protections that dm-verity is intended to provide.
The operational impact of this vulnerability is severe as it enables local privilege escalation without requiring any additional execution privileges, making it particularly dangerous in environments where local access is possible. An attacker who gains access to a device with local privileges can exploit this flaw to modify protected filesystems, potentially gaining elevated access to system resources or bypassing security controls that should prevent such modifications. The lack of requirement for user interaction means that exploitation can occur automatically when the affected system processes the cryptographic verification, making this vulnerability particularly insidious. This type of flaw directly violates the principle of least privilege and can lead to complete system compromise when combined with other exploitation techniques.
Mitigation strategies for CVE-2020-0259 should focus on implementing proper cryptographic validation mechanisms within the dm-verity implementation, ensuring that all cryptographic operations are correctly validated before accepting any filesystem modifications. System administrators should prioritize applying the latest security patches and kernel updates that address this specific vulnerability, as the fix typically involves correcting the cryptographic operation handling within the android_verity_ctr function. Organizations should also implement monitoring for unauthorized filesystem modifications and maintain strict access controls to prevent local privilege escalation opportunities. This vulnerability aligns with CWE-310, which addresses cryptographic issues, and represents a significant concern for mobile device security as it undermines the fundamental integrity protection mechanisms that are critical for maintaining system security. The ATT&CK framework categorizes this as a privilege escalation technique, specifically targeting the modification of system integrity controls through cryptographic weaknesses.