FireEye researchers have warned that a rapidly growing class of Android mobile ad library is collecting sensitive data and is able to perform dangerous operations such as downloading and running new components on demand, remotely. Affecting apps with over 200 million downloads in total, this unnamed ad library, has been dubbed as” Vulna.” ” We have analysed all Android apps with over one million downloads on Google Play, and we found that over 1.8% of these apps used Vulna,” says FireEye,” These affected apps have been downloaded more than 200 million times in total.” Ad libraries enable apps to host advertisements. FireEye has coined the term” vulnaggressive” to describe this class of vulnerable and aggressive characteristics. Most vulnaggresive libraries are proprietary and it’s hard for app developers to know their underlying security issues. Legitimate apps using vulnaggresive libraries present serious threats for enterprise customers. FireEye has informed both Google and the vendor of Vulna about the security issues and they are actively addressing it. Though it is widely known that ad libraries present privacy risks such as collecting device identifiers (IMEI and IMSI), and location information, Vulna presents far more severe security issues. First, Vulna is aggressive – if instructed by its server, it will collect sensitive information such as text messages, phone call history, and contacts. It also performs dangerous operations such as executing dynamically downloaded code. Second, Vulna contains a number of diverse vulnerabilities. For instance it transfers user’s private information over HTTP in plain text, which is vulnerable to eavesdropping attacks. These vulnerabilities when exploited allow an attacker to utilize Vulna’s risky and aggressive functionality to conduct malicious activity, such as turning on the camera and taking pictures without user’s knowledge, stealing two-factor authentication tokens sent via SMS, or turning the device into part of a botnet. There are many possible ways an attacker could exploit Vulna’s vulnerabilities. One example is public WiFi hijacking: when the victim’s device connects to a public WiFi hotspot (such as at a coffee shop or an airport), an attacker nearby could eavesdrop on Vulna’s traffic and inject malicious commands and code. Attackers can also conduct DNS hijacking to attack users around the world, as in the Syrian Electronic Army’s recent attacks targeting Twitter, the New York Times, and Huffington Post. In a DNS hijacking attack, an attacker could modify the DNS records of Vulna’s ad servers to redirect visitors to their own control server, in order to gather information from or send malicious commands to Vulna on the victim’s device. FireEye concludes,” Vulna’s aggressive behaviours and vulnerabilities expose Android users, especially enterprise users, to serious security threats. By exploiting Vulna’s vulnaggressive behaviours, an attacker could download and execute arbitrary code on user’s device within Vulna’s host app.” A solution has not yet been talked about.