We’re seeing reports of exploitation of this vulnerability. We can confirm Global Correlation - Network Participation telemetry is seeing multiple exploitation attempts across many customers. Customers who participate in Global Correlation -- Inspection have a higher chance of this signature blocking in the default configuration since the sensor will take the reputation of an attacker into account during the risk rating evaluation. One of the reports mentioned the use of an IRC-based botnet as a payload for a large number of compromised machines. Since this report is similar to one I previously blogged about, I examined the IRC payloads in depth. Many of the variable names and functions are identical, with the new bot’s source code indicating that it is a later revision of the one we saw previously. Additional features have been added in this revision, which can allow the bots to transfer files directly to other bots via the command and control channel. Given the nature of this vulnerability and the ease of exploitation, it is very likely that unpatched machines will continue to be compromised if not remediated.
A 0-day vulnerability has been publicly posted which affects older versions of the Parallels Plesk software. The author of the exploit included an informational text file, which appears to indicate public servers have already been exploited. This vulnerability does not affect the latest major version of the software; nevertheless we expect to see widespread exploitation, due to the age of the affected versions — sites still running these versions of Plesk, which should enter End of Life of June 9, are unlikely to be regularly maintained.