On Saturday, a malware researcher known online as Kafeine spotted a drive-by download attack done with the Magnitude exploit kit that was exploiting a Flash Player vulnerability patched Tuesday.
The flaw, tracked as CVE-2015-3113 in the Common Vulnerabilities and Exposures database, had zero-day status -- that is, it was previously unpatched -- when Adobe released a patch for it. It had already been exploited by a China-based cyberespionage group for several weeks in targeted attacks against organizations from the aerospace, defense, construction, engineering, technology, telecommunications and transportation industries.
It is not unusual to see zero-day exploits for Flash Player and other popular applications being used in highly targeted cyberespionage attacks. That's because the goal of the attackers behind them is to compromise organizations that sometimes have sophisticated defenses and to remain undetected for as long as possible.
On the other hand, while zero-day exploits have been used in more indiscriminate, large-scale attacks, such incidents are rare. That's because zero-day vulnerabilities are extremely valuable and it doesn't make financial sense for attackers to burn them in noisy campaigns where they'll be very quickly discovered and patched.
Therefore, it's much more common for the creators of commercial exploit kits like Magnitude to integrate exploits for already patched vulnerabilities. For them it's a numbers game and there's always a large number of users who fail to install updates in a timely manner if at all.
But it seems that while computer users have not significantly improved their patching times, the exploit kit creators are aggressively reducing the time they need to integrate exploits.
The new Magnitude attacks left users with only four days to install the Flash Player patch for CVE-2015-3113, a very small time frame especially for organizations that typically deploy updates according to predetermined schedules that are often more than one week apart.
Earlier this year the authors of another exploit kit, Nuclear EK, integrated a Flash Player exploit a week after Adobe patched it, signaling a trend toward increasingly smaller patch windows.
The new Magnitude attacks that exploit CVE-2015-3113, if successful, install the Cryptowall ransomware. However, the payload could be changed by the attackers to something else at any time.