CVE-2019-16248 in Telegram
Summary
by MITRE
The "delete for" feature in Telegram before 5.11 on Android does not delete shared media files from the Telegram Images directory. In other words, there is a potentially misleading UI indication that a sender can remove a recipient's copy of a previously sent image (analogous to supported functionality in which a sender can remove a recipient's copy of a previously sent message).
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Analysis
by VulDB Data Team • 12/19/2023
The vulnerability identified as CVE-2019-16248 represents a critical privacy and data retention issue within Telegram's Android application prior to version 5.11. This flaw specifically impacts the deletion functionality for shared media content, creating a significant mismatch between user expectations and actual system behavior. The vulnerability stems from the inconsistent implementation of the "delete for" feature which operates differently for text messages versus media files, leading to potential data exposure and privacy violations.
The technical flaw manifests in the Android implementation where the "delete for" functionality correctly removes text messages from recipients' devices but fails to properly purge shared media files from the Telegram Images directory. This creates a scenario where users believe they have completely removed media content from conversations, while the actual media files persist in the device's storage. The issue is particularly concerning because it violates the principle of least privilege and data minimization, as users cannot effectively control their media data retention. From a cybersecurity perspective, this vulnerability represents a data leakage vector that could expose sensitive information contained within shared images.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential security risks for users handling sensitive or confidential media content. Attackers could exploit this behavior to recover previously deleted images from compromised devices, potentially accessing information that users believed had been permanently removed. The misleading UI indication creates a false sense of security, leading users to make incorrect assumptions about their data protection status. This vulnerability affects the fundamental trust users place in Telegram's privacy features and could be particularly damaging for users in high-risk environments where media content might contain sensitive information.
This vulnerability aligns with CWE-200 (Information Exposure) and CWE-312 (Sensitive Data Exposure) categories, as it involves the improper handling of user data and the exposure of information that should have been deleted. The issue also maps to ATT&CK technique T1537 (Transfer Data to Cloud Account') and T1566 (Phishing') as it could enable adversaries to recover deleted content and potentially use it for social engineering attacks. The persistent media files in the Telegram Images directory create a data repository that could be accessed through various attack vectors including device compromise, forensic analysis, or unauthorized access to backup systems.
The recommended mitigations include immediate upgrade to Telegram version 5.11 or later where the fix has been implemented, along with user education about the potential persistence of media files even after deletion operations. Organizations should conduct security awareness training to ensure users understand the limitations of deletion features and consider implementing additional data handling policies for sensitive content. Regular security audits should verify that all media deletion operations function correctly across different content types, and system administrators should monitor for any unusual access patterns to shared media directories. Additionally, users should be advised to manually verify the complete removal of sensitive content through file system inspection when dealing with critical information.