CVE-2022-23835 in Visual Voice Mail
Summary
by MITRE • 02/25/2022
** DISPUTED ** The Visual Voice Mail (VVM) application through 2022-02-24 for Android allows persistent access if an attacker temporarily controls an application that has the READ_SMS permission, and reads an IMAP credentialing message that is (by design) not displayed to the victim within the AOSP SMS/MMS messaging application. (Often, the IMAP credentials are usable to listen to voice mail messages sent before the vulnerability was exploited, in addition to new ones.) NOTE: some vendors characterize this as not a "concrete and exploitable risk."
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/03/2024
The vulnerability described in CVE-2022-23835 resides within the Visual Voice Mail application for Android systems, specifically affecting versions through February 24, 2022. This security flaw represents a sophisticated persistence mechanism that leverages the legitimate READ_SMS permission granted to certain applications. The vulnerability operates through a design flaw where IMAP credential messages are intentionally not displayed to end users within the standard Android SMS/MMS messaging interface, creating a hidden communication channel that attackers can exploit. This design decision, while intended to maintain user experience by filtering out technical credential messages, inadvertently creates a security vector that adversaries can manipulate for unauthorized access. The vulnerability's classification as disputed by some vendors stems from the requirement for specific preconditions including temporary control of an application with READ_SMS permission, making it less straightforward than typical exploitable vulnerabilities.
The technical implementation of this vulnerability involves the manipulation of the Android messaging ecosystem's permission model and message handling processes. When an attacker gains temporary control of an application possessing READ_SMS permission, they can access and read IMAP credential messages that contain authentication details for voice mail services. These messages are designed to be invisible to regular users within the standard messaging application, but the attacker can extract and utilize this information to establish persistent access to voice mail accounts. The credential messages typically contain session tokens or authentication parameters that allow attackers to access not only future voice mail messages but also previously recorded messages that were sent before the exploitation occurred. This temporal aspect of the vulnerability significantly amplifies its impact, as it provides access to historical voice mail content that may contain sensitive information, potentially including business communications, personal data, or confidential conversations.
The operational impact of this vulnerability extends beyond simple unauthorized access to voice mail services. The persistence aspect of this flaw means that once an attacker successfully exploits it, they can maintain access to voice mail accounts without requiring repeated exploitation attempts. The vulnerability affects the fundamental trust model of mobile messaging applications, where users expect that messages containing sensitive credential information will remain protected and inaccessible to unauthorized parties. This breach of trust represents a significant compromise to mobile security, particularly in enterprise environments where voice mail systems often contain sensitive business communications. The vulnerability also demonstrates weaknesses in Android's permission model and message filtering mechanisms, suggesting potential gaps in how the operating system handles different types of messages and their visibility to applications with specific permissions. From a security perspective, this vulnerability represents a case where legitimate design choices in user experience inadvertently create security weaknesses that attackers can exploit.
Mitigation strategies for CVE-2022-23835 should focus on both immediate application-level fixes and broader system security improvements. Application vendors must ensure that credential messages are properly filtered and protected from unauthorized access even when applications possess READ_SMS permissions. The implementation of additional access controls or message categorization systems can prevent unauthorized applications from accessing sensitive credential information. System-level mitigations include enhanced monitoring of applications with READ_SMS permissions and implementing stricter controls over how these permissions are granted and used. Organizations should conduct regular security assessments to identify applications that may be inadvertently exposing sensitive information through legitimate permissions. This vulnerability also highlights the importance of secure coding practices and the need for security reviews of messaging applications to ensure that design decisions don't create unintended security vectors. The security community should consider this vulnerability in the context of broader mobile security frameworks and ATT&CK techniques related to credential access and persistence mechanisms, as it represents a sophisticated approach to maintaining long-term access through legitimate system interfaces. The vulnerability's classification as disputed underscores the need for careful risk assessment and the importance of understanding the specific conditions under which such vulnerabilities can be exploited within different organizational contexts.