How Hackers Bypassed an Adobe Flash Protection Mechanism
The number of Flash Player exploits has recently declined, due to Adobe’s introduction of various measures to strengthen Flash’s security. Occasionally, however, an exploit still arises. On January 31, Kr-Cert reported a zero-day vulnerability, identified as CVE-2018-4878, being exploited in the field.
(Adobe has released an update to fix this flaw.) We analyzed this vulnerability and found that it bypassed the byte array mitigation feature that was introduced to prevent “length corruption” attacks in Flash. This post will focus on how the exploit bypasses the length checks.