For the second time in as many months, networks around the world have been attacked using a worming ransomware that gains new infections by exploiting a recently-patched Windows SMB vulnerability among other proven techniques. What has been described a ransomware bearing significant similarities to the Petya encryption ransomware ravaged numerous companies and networks around the world with disproportionate impact in Ukraine and Eastern Europe but also inflicted harm to significant numbers of victims in Western Europe and North America.
The WannaCry ransomware incident has galvanized global media coverage and dominated discussion among information security professionals since Friday, May 12. The speed with which this malware was able to spread within enterprise networks and how rapidly so many large organizations were impacted is unsettling. Yet, as the dust begins to settle, it is clear that this episode has left a number of lessons in its wake–lessons to be harnessed by defenders and their adversaries.
While this attack is an expansive topic that will continue to evolve as more discoveries are made about the impact, origin, and spread of the WannaCry ransomware, it is also important to keep in mind that WannaCry is one of three major incidents to arise in the past month. Lessons provided by WannaCry are only deepened by the additional context of the fake Google Docs malicious cloud application incident of May 4, 2017 and the introduction of the Jaff encryption ransomware on May 11, 2017. First and most obvious, both Jaff and WannaCry show that the ransomware business model is far from obsolete. There is still a great deal of value to threat actors in holding data for ransom. Second, the novel attack vectors for WannaCry and the fake Google Docs cloud application show that innovation in leveraging new attack surfaces is happening among threat actors. The challenge for defenders is to internalize these revelations and develop an agile security posture that incorporates defense against existing risks and emergent attack vectors.
The explosive growth of ransomware in 2016 marked a dramatic shift in how many threat actors monetize phishing attacks. While certain ransomware tools were delivered using other mechanisms, tools like Locky and Cerber set the tone for the ransomware business model. These ransomware tools were delivered by massive numbers of phishing email to reach the largest number of victims. This business model has been once again put into action by the Jaff encryption ransomware following its debut just one week ago on May 11, 2017. However, the worm functionality demonstrated by WannaCry puts a unique spin on that model by reducing the infrastructure and resource expenditure necessary for the threat actor to maximize their ability to infect new hosts. The goal for both Jaff and WannaCry threat actors is still to reach as many victims as possible to maximize the number of potential ransom payments, lending credence to the notion that ransomware is far from obsolete as an avenue for online crime.
While the propagation mechanisms of the fake “Google Docs” application that made headlines on May 4, 2017 and the WannaCry ransomware worm differ dramatically, both show that virulence is an important aspect of their overall strategy. Furthermore, each of these incidents shows a significant level of innovation by harnessing relatively new attack vectors. The fake “Google Docs” incident took advantage of users’ reliance on cloud services to propagate while WannaCry leveraged a vulnerability only recently disclosed and made public. However effective these attacks were in their own right, the long-term impact will be the future attacks inspired by these innovations. Whether the payload is a ransomware or some other category of malware, threat actors are watching and learning from these attacks. Furthermore, neither innovation is exclusive of the use phishing email as a means for making a “first contact” with a victim as was the case with the fake “Google Docs” application. By combining these promising innovations with a tried-and-trusted attack vector, threat actors will continue to gain access to enterprise data and hold it for ransom.
The high profile events of the past month have provided some indication that threat actors are quickening the pace of innovation and looking to combine these innovations with existing attack models. Both phishing and the ransomware tools delivered via phishing emails have proven very successful for threat actors and continued use of both can be expected. However, as threat actors learn from events like those from the past month it can be expected that they will attempt to implement their own versions using creative re-combinations of these techniques to launch attacks of their own.
To anticipate and mitigate these new attack vectors, those tasked with defending enterprises must adapt their security posture to changing paradigms. It is important to ensure there are agile defense and response processes that incorporate protections for multiple attack surfaces and at various stages of the attack life cycle. This effort begins with the basics of regular patching and network hygiene. It also requires the anticipatory education and empowerment of email users to engage with messages critically and act on suspicions, reporting potentially-malicious emails to the enterprise’s defenders. These internal reports can then be compared to external observations and intelligence reporting to identify the most immediate risks to an organization. The threat landscape is evolving, but in the face of robust, holistic, and human-centered defense strategies, attackers can be overcome.
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Adding another entry to the ever-growing list of encryption ransomware, the Jaff Ransomware made its debut onto the threat landscape with large sets of phishing emails on May 11, 2017 – one day before the sensational impact of the WannaCry ransomware attack. However, the risks posed by the Jaff ransomware should not be overlooked. This, too, is a robust ransomware that leverages some of the most prolifically-used delivery mechanisms in phishing email and embodies characteristics associated with other very successful malware.
The ransomware that defined much of the phishing threat landscape in 2016 raged back into prominence on April 21, 2017 with multiple sets of phishing email messages. Harkening back to narratives used throughout 2016, these messages leveraged simple, easily-recognizable, but perennially-effective phishing lures to convince recipients to open the attached file.
Threat actors using the Dridex botnet malware received a great deal of attention recently for their purported utilization of content exploiting a previously un-patched vulnerability in Microsoft Word. This exploit, which took advantage of unexpected behavior in the handling of certain document types, was reportedly used to deliver the Dridex botnet malware via documents attached to phishing emails. However, the bulk of Dridex campaigns leverage far more common delivery techniques that abuse the functionality that already exists in Microsoft Office and Adobe Reader rather than deploying some complex exploit content. This serves as a reminder that threat actors don’t always rely on exploit content because exploits of un-patched vulnerabilities are no longer required to break into an enterprise; simple phishing messages can accomplish this same goal.
WARNING: MAJOR SPOILER ALERT!
USA Network’s television show, Mr.Robot, kicked off Season 2 with a BANG! The program features the exploits of a hacker named Elliot Alderson (Rami Malek) who uses the alias “Mr.Robot” to work with a team of hackers who call themselves F-Society and have as their mission the destruction of a major corporation that they call “Evil Corp,” whose logo calls back to the Big Corporate Corruption of Enron. In this episode, the attack is against the “Bank of E.”
Your computer is infected! Pay $50 USD in order to remove the malware.
The FBI has been tracking you for visiting inappropriate sites. Please pay $250 to avoid higher court costs and appearances.
Ransomware is nothing new, and typically comes in many shapes and sizes. For years, users have been visiting websites, only to be redirected to a ransomware site and scared into paying fees that amounted to nothing more than lost money. With the advent of CryptoLocker, however, attackers have felt a need to “give” back to their victims. Once they infect a system and encrypt the data, they will offer to decrypt this data for a small fee. How kind of them…
In recent months, attackers have started to change the game by delivering these samples via phishing, and using new malware that imitates Cryptolocker. I recently came across a phish carrying ransomware similar to Cryptolocker, but with some noteworthy differences.