The Russia-linked threat actor known as Pawn Storm ramped up its attacks against governments and embassies after seeing that researchers discovered the Windows and Flash Player zero-day exploits it had been using.
In late October, Google disclosed a serious Windows kernel vulnerability that had been exploited in the wild. Microsoft was informed about the issue on October 21, but it only managed to release a patch this week. Microsoft was unhappy with Google’s decision, but it quickly provided some mitigations.
Microsoft revealed in early November that the Pawn Storm group, which it calls Strontium, exploited the Windows flaw (CVE-2016-7255) in combination with a Flash Player vulnerability (CVE-2016-7855). Google also reported the Flash Player bug to Adobe on October 21, but unlike Microsoft, Adobe released a patch after only a few days.
Trend Micro has been monitoring Pawn Storm, which is also known as APT28, Fancy Bear, Sednit, Sofacy and Tsar Team. According to the security firm, Pawn Storm initially used the two zero-days only against very high-profile targets.
Then, after the existence of the flaws was disclosed and Adobe released patches, the threat actor sent several waves of spear-phishing emails to embassies and other government agencies. Starting with early November, the cyberspies used the zero-days in attacks aimed at various governments around the world.
The vulnerabilities have been used against an increasing number of targets, which suggests that they started losing their value following Google’s disclosure.
Trend Micro spotted several types of spear-phishing emails used in these attacks. Some of them appeared to advertise Defence IQ’s Cyber Threat Intelligence and Incident Response conference. The emails carried specially crafted RTF documents that included a malicious Flash file designed to download an exploit for CVE-2016-7855.
Another attack involved emails with the subject line “European Parliament statement on nuclear threats.” These fake messages purported to come from the European Union’s media relations office and they included links that led to Pawn Storm’s exploit kit.