Executive Summary

[{'type': 'paragraph', 'content': "CVE-2025-69621 is an arbitrary file overwrite vulnerability in the Comic Book Reader app version 1.0.95. It occurs in the app's file import process, specifically in the MainActivity component, due to insufficient security validation when handling imported files."}, {'type': 'paragraph', 'content': "An attacker can exploit this flaw by manipulating the filename and content of imported files using path traversal sequences. This allows overwriting of critical internal files stored in the app's private storage, such as configuration files like WebViewChromiumPrefs.xml."}, {'type': 'paragraph', 'content': 'The vulnerability can be triggered with minimal user interaction, for example, by opening a malicious app that sends a crafted intent to the vulnerable app. This can lead to severe consequences including arbitrary code execution, exposure of sensitive information, denial of service, or causing the app to malfunction.'}] [2]

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Impact Analysis

[{'type': 'paragraph', 'content': 'This vulnerability can have serious impacts on users of the Comic Book Reader app. An attacker can overwrite critical internal files, potentially leading to:'}, {'type': 'list_item', 'content': "Arbitrary code execution, allowing the attacker to run malicious code within the app's context."}, {'type': 'list_item', 'content': "Exposure of sensitive information stored in the app's private files."}, {'type': 'list_item', 'content': 'Denial of service by causing the app to malfunction or fail to launch.'}, {'type': 'list_item', 'content': 'Overall compromise of app integrity and user data security.'}, {'type': 'paragraph', 'content': 'The attack requires minimal user interaction and can be triggered automatically when the victim opens a malicious app.'}] [2]

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Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability can be detected by monitoring for suspicious intents or URI requests targeting the Comic Book Reader app's MainActivity with path traversal payloads in the _display_name parameter. Specifically, detection involves identifying attempts to exploit the file import process by overwriting internal files such as configuration files."}, {'type': 'paragraph', 'content': 'Since the attack uses specially crafted intents with ACTION_VIEW and malicious URIs, you can look for unusual intent invocations or content provider accesses that include path traversal sequences (e.g., ../) in the filename parameters.'}, {'type': 'paragraph', 'content': 'On an Android device or emulator, you might use commands like the following to detect suspicious activity:'}, {'type': 'list_item', 'content': "adb logcat | grep 'ru.androidtools.comic_book_magazine_reader_cbr_cbz'"}, {'type': 'list_item', 'content': "adb shell dumpsys activity intents | grep 'ACTION_VIEW'"}, {'type': 'list_item', 'content': 'adb shell run-as ru.androidtools.comic_book_magazine_reader_cbr_cbz ls -l /data/data/ru.androidtools.comic_book_magazine_reader_cbr_cbz/shared_prefs/'}, {'type': 'paragraph', 'content': "These commands help identify if the app's internal files have been modified or if suspicious intents have been triggered. Additionally, monitoring for unusual file changes in the app's private storage, especially configuration files like WebViewChromiumPrefs.xml, can indicate exploitation attempts."}] [2]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'Immediate mitigation steps include restricting or disabling the vulnerable file import functionality in Comic Book Reader v1.0.95 to prevent arbitrary file overwrite.'}, {'type': 'paragraph', 'content': 'You should also avoid opening files or intents from untrusted sources that could exploit the path traversal vulnerability.'}, {'type': 'paragraph', 'content': 'If possible, update the application to a patched version that properly validates and sanitizes filenames during the import process to prevent path traversal attacks.'}, {'type': 'paragraph', 'content': "As a temporary measure, monitor and restrict other apps from sending intents with ACTION_VIEW targeting the vulnerable app's MainActivity."}, {'type': 'paragraph', 'content': 'Finally, consider backing up critical app data and configuration files to recover from any potential overwrites.'}] [2]

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Compliance Impact

The vulnerability allows attackers to overwrite critical internal files, potentially leading to arbitrary code execution or exposure of sensitive information.

Exposure of sensitive information due to this vulnerability could lead to non-compliance with data protection regulations such as GDPR or HIPAA, which require safeguarding personal and sensitive data against unauthorized access or breaches.

Additionally, the ability to execute arbitrary code or cause denial of service may compromise the integrity and availability of the application, further impacting compliance with standards that mandate secure and reliable systems.

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