Hackers can steal 2FA codes and private messages from Android phones

Summary

In the second step, Pixnapping performs graphical operations on individual pixels that the targeted app sent to the rendering pipeline. These operations choose the coordinates of target pixels the app wants to steal and begin to check if the color of those coordinates is white or non-white. “Suppose, for example, [the attacker] wants to steal a pixel that is part of the screen region where a 2FA character is known to be rendered by Google Authenticator,” Wang said. “This pixel is either white (if nothing was rendered there) or non-white (if part of a 2FA digit was rendered there). Then, conceptually, the attacker wants to cause some graphical operations whose rendering time is long if the target victim pixel is non-white and short if it is white. The malicious app does this by opening some malicious activities (i.e., windows) in front of the victim app that was opened in Step 1.” The third step measures the amount of time required at each coordinate. By combining the times for each one, the attack can rebuild the images sent to the rendering pipeline one pixel at a time. The amount of time required to perform the attack depends on several variables, including how many coordinates need to be measured. In some cases, there’s no hard deadline for obtaining the information the attacker wants to steal. In other cases—such as stealing a 2FA code—every second counts, since each one is valid for only 30 seconds. In the paper, the researchers explained: To meet the strict 30-second deadline for the attack, we also reduce the number of samples per target pixel to 16 (compared to the 34 or 64 used in earlier attacks) and decrease the idle time between pixel leaks from 1.5 seconds to 70 milliseconds. To ensure that the attacker has the full 30 seconds to leak the 2FA code, our implementation waits for the beginning of a new 30-second global time interval, determined using the system clock. ... We use our end-to-end attack to leak 100 different 2FA codes from Google Authenticato...