CVE-2016-4595 in Mac OS X
Summary
by MITRE
Safari Login AutoFill in Apple OS X before 10.11.6 allows physically proximate attackers to discover passwords by reading the screen during the login procedure.
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Analysis
by VulDB Data Team • 10/01/2024
The vulnerability identified as CVE-2016-4595 represents a significant security flaw in Apple's Safari web browser implementation within macOS versions prior to 10.11.6. This issue specifically affects the Login AutoFill functionality that automatically suggests and fills login credentials when users visit websites that require authentication. The vulnerability stems from insufficient screen protection mechanisms during the login process, creating a window of opportunity for attackers who are physically present near the target device.
The technical nature of this flaw lies in the timing and display behavior of password fields during the Safari auto-fill process. When users navigate to websites requiring login credentials, the system temporarily displays password suggestions or auto-filled values on screen before the user completes the authentication process. This exposure occurs due to inadequate screen clearing or masking mechanisms that should prevent sensitive information from being visible to unauthorized observers. The vulnerability is classified under CWE-200 as exposure of sensitive information to an unauthorized actor, specifically through screen content disclosure during authentication procedures.
Attackers exploiting this vulnerability can gain unauthorized access to password information by simply observing the screen during the brief window when auto-fill suggestions appear. This type of attack falls under the ATT&CK framework category of Credential Access through OS Credential Dumping and Screen Capture techniques, where adversaries leverage physical proximity to capture sensitive information. The attack vector is particularly concerning because it requires minimal technical skill and can be executed by anyone physically present near the target device, making it a significant risk in shared or public environments where users might be unaware of their surroundings.
The operational impact of this vulnerability extends beyond individual user accounts to potentially compromise entire organizational security postures. Users who frequently access web applications with auto-fill enabled become vulnerable to shoulder-surfing attacks, where attackers observe login procedures to harvest credentials. This risk is amplified in corporate environments where employees might be working in open office spaces or public areas where physical security controls are inadequate. The vulnerability affects the fundamental security principle of least privilege by allowing unauthorized information disclosure without requiring network access or complex exploitation techniques.
Mitigation strategies for this vulnerability include upgrading to macOS 10.11.6 or later versions where Apple implemented proper screen protection mechanisms during the auto-fill process. Organizations should also implement additional physical security measures such as screen filters, secure work environments, and user awareness training about the risks of shoulder-surfing attacks. System administrators should consider implementing additional authentication layers such as multi-factor authentication to reduce the impact of credential compromise. The fix implemented by Apple involved enhancing the screen clearing behavior during auto-fill operations, ensuring that password information is properly masked or cleared before the user completes the authentication process, thereby preventing unauthorized visual access to sensitive credentials.