[Background] Web communication is universal in cyberspace, and security risks in this domain are devastating. [Aims] We analyzed the prevalence of six security smells in mobile app servers, and we investigated the consequence of these smells from a security perspective. [Method] We used an existing dataset that includes 9 714 distinct URLs used in 3 376 Android mobile apps. We exercised these URLs twice within 14 months and investigated the HTTP headers and bodies. [Results] We found that more than 69% of tested apps suffer from three kinds of security smells, and that unprotected communication and misconfigurations are very common in servers. Moreover, source-code and version leaks, or the lack of update policies expose app servers to security risks. [Conclusions] Poor app server maintenance greatly hampers security.

IT professionals have no simple tool to create phishing websites and raise the awareness of users. We developed a prototype that can dynamically mimic websites by using enriched screenshots, which requires no additional programming experience and is simple to set up. The generated websites are functional and remain up-to-date. We found that 98% of the hyperlinks in mimicked websites are functional with our tool, compared to 43 % with the best competitor, and only two participants suspected phishing attempts at the time they were performing tasks with our prototype. This work intends to raise awareness for phishing attempts especially with local websites by providing an easy to use prototype to set up such phishing sites.

HTTP headers are commonly used to establish web communications, and some of them are relevant for security. However, we have only little information about the usage and support of security-relevant headers in mobile applications. We explored the adoption of such headers in mobile app communication by querying 9 714 distinct URLs that were used in 3 376 apps and collected each server's response information. We discovered that support for secure HTTP header fields is absent in all major HTTP clients, and it is barely provided with any server response. Based on these results, we discuss opportunities for improvement particularly to reduce the likelihood of data leaks and arbitrary code execution. We advocate more comprehensive use of existing HTTP headers and timely development of relevant web browser security features in HTTP client libraries.

Web communication has become an indispensable characteristic of mobile apps. However, it is not clear what data the apps transmit, to whom, and what consequences such transmissions have. We analyzed the web communications found in mobile apps from the perspective of security. We first manually studied 160 Android apps to identify the commonly-used communication libraries, and to understand how they are used in these apps. We then developed a tool to statically identify web API URLs used in the apps, and restore the JSON data schemas including the type and value of each parameter. We extracted 9714 distinct web API URLs that were used in 3 376 apps. We found that developers often use the java.net package for network communication, however, third-party libraries like OkHttp are also used in many apps. We discovered that insecure HTTP connections are seven times more prevalent in closed-source than in open-source apps, and that embedded SQL and JavaScript code is used in web communication in more than 500 different apps. This finding is devastating; it leaves billions of users and API service providers vulnerable to attack.

The ubiquity of smartphones, and their very broad capabilities and usage, make the security of these devices tremendously important. Unfortunately, despite all progress in security and privacy mechanisms, vulnerabilities continue to proliferate.,,Research has shown that many vulnerabilities are due to insecure programming practices. However, each study has often dealt with a specific issue, making the results less actionable for practitioners. To promote secure programming practices, we have reviewed related research, and identified avoidable vulnerabilities in Android-run devices and the security code smells that indicate their presence. In particular, we explain the vulnerabilities, their corresponding smells, and we discuss how they could be eliminated or mitigated during development. Moreover, we develop a lightweight static analysis tool and discuss the extent to which it successfully detects several vulnerabilities in about 46 000 apps hosted by the official Android market.