CVE-2020-27940 in TV App
Summary
by MITRE • 09/08/2021
This issue was addressed with improved file handling. This issue is fixed in Apple TV app for Fire OS 6.1.0.6A142:7.1.0. An attacker with file system access may modify scripts used by the app.
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Analysis
by VulDB Data Team • 09/10/2021
The vulnerability described in CVE-2020-27940 represents a significant security flaw in the Apple TV application running on Fire OS platforms. This issue stems from inadequate file handling mechanisms that allow unauthorized modifications to critical application components. The vulnerability specifically affects versions prior to 6.1.0.6A142:7.1.0 where the application fails to properly validate or secure the file system access permissions for script files that are integral to its operation. The flaw creates a dangerous attack surface where malicious actors with legitimate file system access can manipulate the application's underlying scripts, potentially leading to arbitrary code execution or complete application compromise.
The technical nature of this vulnerability aligns with CWE-732, which describes improper limitation of a pathname to a restricted directory, and CWE-22, which covers improper limitation of a pathname to a restricted directory. The root cause lies in the application's failure to implement proper file access controls and validation mechanisms for script files. When an attacker gains file system access, they can directly modify the scripts that the Apple TV app relies upon, effectively allowing them to alter the application's behavior and potentially execute malicious code. This type of vulnerability demonstrates a fundamental breakdown in the principle of least privilege and proper input validation.
From an operational perspective, this vulnerability presents a severe risk to users of Fire OS devices running affected versions of the Apple TV application. The attack vector requires only file system access, which may be obtained through various means including physical device access, compromised user accounts, or exploitation of other vulnerabilities that grant file system privileges. The impact extends beyond simple script modification as attackers could potentially inject malicious code into the application's execution flow, leading to persistent backdoors, data exfiltration, or complete system compromise. This vulnerability undermines the integrity of the application and could be leveraged as a stepping stone for further attacks within the device's operating environment.
The mitigation strategy for this vulnerability focuses primarily on updating to the patched version 6.1.0.6A142:7.1.0 or later, which implements improved file handling mechanisms that prevent unauthorized script modifications. Organizations should conduct immediate inventory checks to identify all affected devices and ensure timely deployment of the security update. Additionally, system administrators should review and enforce proper file system access controls, implementing the principle of least privilege to minimize the attack surface. The fix addresses the underlying file handling implementation by introducing proper validation checks and access controls that prevent modification of critical application scripts. Security monitoring should be enhanced to detect any suspicious file system modifications that might indicate exploitation attempts, aligning with ATT&CK technique T1070.006 for Indicator Removal on Host. The resolution demonstrates the importance of proper file system security practices and the necessity of continuous security updates in mobile and embedded operating systems.