Adobe may have already patched a Flash Player vulnerability last week, but several users—especially those in the US, Canada, and the UK —are still currently exposed and are at risk of getting infected with CryptoWall 3.0. The Magnitude Exploit Kit included an exploit, detected as SWF_EXPLOIT.MJTE, for the said vulnerability, allowing attackers to spread crypto-ransomware into their target systems. We first saw signs of this activity yesterday, June 15, through our monitoring of threat intelligence from the Trend Micro™ Smart Protection Network™.
This particular vulnerability, identified as CVE-2015-3105, was fixed as part of Adobe’s regular June Update for Adobe Flash Player which upgraded the software to version 188.8.131.52. However, many users are still running the previous version (184.108.40.206), which means that a lot of users are still at risk.
As of this week, these are the top 10 countries most affected by this threat:
- United States
Ongoing Exploit Problem
This is another example of how cybercriminals rapidly take advantage of recently-patched vulnerabilities through exploit kits. We saw a similar incident in March, where exploits for an Adobe Flash Player vulnerability were added to the Nuclear Exploit Kit just a week after the patch was released. We also noted earlier this month that Flash Player was being targeted more frequently by exploit kits, and that shows no sign of changing soon.
Figure 1. Flash version used in testing
The SWF sample we acquired is heavily obfuscated using secureSWF, and uses two shaders for the actual exploit code.
Figure 2. Shaders used in exploit code
Widely-used exploit kits such as Magnitude are often well-maintained with new vulnerabilities. Our research on these tools reveals that Magnitude is one of the most used exploit kits by cybercriminals along with SweetOrange and Angler.
CryptoWall is also another notable threat in and of itself. We initially saw CryptoWall last year spreading through spam, and again later this year partnering with information stealing malware FAREIT.
Figure 3. Ransomware demand page
Trend Micro is already able to protect users against this threat. The existing Sandbox with Script Analyzer engine, which is part of Trend Micro™ Deep Discovery, can be used to detect this threat by its behavior without any engine or pattern updates. Meanwhile, the Browser Exploit Prevention feature in the Endpoint Security in Trend Micro™ Smart Protection Suite blocks the exploit once the user accesses the URL it is hosted in. Browser Exploit Prevention protects against exploits that target browsers or related plugins.
We recommend that users stay up-to-date with the latest Flash Player version, and this incident is an excellent reminder of just how important it is to do so. We also note that Google Chrome automatically updates its own included version of Flash Player.
The malicious Adobe Flash exploit is detected as SWF_EXPLOIT.MJTE. Below is its SHA1:
With Additional analysis by Brooks Li and Joseph C Chen
Update as of June 16, 2015, 8:30 A.M. PST:
We have updated the entry to include the detection name for the exploit.