CVE-2015-3888 in Sailfish OS
Summary
by MITRE
Jolla Sailfish OS before 1.1.2.16 allows remote attackers to spoof phone numbers and trigger calls to arbitrary numbers via spaces in a tel: URL.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 12/22/2019
The vulnerability identified as CVE-2015-3888 affects Jolla Sailfish OS versions prior to 1.1.2.16 and represents a significant security flaw in the telephony handling mechanism of the operating system. This issue stems from inadequate input validation within the tel: URL parsing functionality, which is commonly used for initiating phone calls through web browsers and applications. The vulnerability enables remote attackers to manipulate the phone number parsing process by exploiting whitespace characters within the URL structure, potentially leading to unauthorized calling activities and privacy violations.
The technical implementation of this vulnerability occurs when the Sailfish OS processes tel: URLs containing spaces that separate the phone number from additional parameters or commands. The operating system fails to properly sanitize and validate the phone number portion of these URLs, allowing attackers to inject malicious phone numbers that bypass normal validation checks. This parsing error creates a path for command injection attacks where spaces within the URL can be interpreted as delimiters, causing the system to extract and execute unintended phone numbers from the URL string. The flaw specifically affects the call initiation functionality and can be exploited through various attack vectors including malicious web pages, phishing campaigns, or compromised applications that generate or process tel: URLs.
The operational impact of CVE-2015-3888 extends beyond simple privacy concerns to encompass potential financial fraud, unauthorized communications, and privacy violations. Attackers can leverage this vulnerability to trigger calls to premium rate numbers, international destinations, or emergency services without user consent, potentially resulting in unauthorized charges or emergency response protocols being activated. The remote exploitation capability means that users can be targeted through web browsing activities, making this a particularly dangerous vulnerability for mobile users. Additionally, the vulnerability could enable attackers to perform reconnaissance activities by testing various phone number formats or to conduct social engineering attacks by making calls appear to originate from legitimate sources through number spoofing techniques.
This vulnerability aligns with CWE-20, which addresses "Improper Input Validation," and demonstrates weaknesses in URL parsing and phone number validation mechanisms. The issue also relates to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript" and T1190 for "Exploit Public-Facing Application" as attackers can exploit web-based interfaces to trigger the vulnerable functionality. The vulnerability represents a classic example of how improper handling of user-supplied data can lead to arbitrary code execution or unauthorized system actions, particularly in mobile operating systems where telephony functions are tightly integrated with application frameworks. The security implications extend to user trust and system integrity, as the vulnerability can be exploited to perform actions that users never intended to authorize.
Mitigation strategies for CVE-2015-3888 include immediate upgrade to Sailfish OS version 1.1.2.16 or later, which contains proper input validation and URL sanitization mechanisms. Organizations should also implement network-level filtering to block malicious tel: URL traffic and consider deploying mobile device management solutions that can restrict telephony functionality. Users should be educated about the risks of visiting untrusted websites and should avoid clicking on suspicious links that might contain malicious tel: URLs. System administrators should monitor for unusual telephony activity patterns that might indicate exploitation attempts. The fix implemented by Jolla likely involves enhanced URL parsing routines that properly handle whitespace characters and validate phone number formats before initiating call operations, preventing the injection of malicious numbers through URL manipulation techniques.