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National Cyber Awareness System: 10/22/2014 05:28 PM EDT
Original release date: October 22, 2014
Systems AffectedMicrosoft Windows OverviewRansomware is a type of malicious software (malware) that infects a computer and restricts access to it until a ransom is paid to unlock it. This Alert is the result of Canadian Cyber Incident Response Centre (CCIRC) analysis in coordination with the United States Department of Homeland Security (DHS) to provide further information about crypto ransomware, specifically to:
DescriptionWHAT IS RANSOMWARE?Ransomware is a type of malware that infects a computer and restricts a user’s access to the infected computer. This type of malware, which has now been observed for several years, attempts to extort money from victims by displaying an on-screen alert. These alerts often state that their computer has been locked or that all of their files have been encrypted, and demand that a ransom is paid to restore access. This ransom is typically in the range of $100–$300 dollars, and is sometimes demanded in virtual currency, such as Bitcoin. Ransomware is typically spread through phishing emails that contain malicious attachments and drive-by downloading. Drive-by downloading occurs when a user unknowingly visits an infected website and malware is downloaded and installed without their knowledge. Crypto ransomware, a variant that encrypts files, is typically spread through similar methods, and has been spread through Web-based instant messaging applications. WHY IS IT SO EFFECTIVE?The authors of ransomware instill fear and panic into their victims, causing them to click on a link or pay a ransom, and inevitably become infected with additional malware, including messages similar to those below:
PROLIFERATION OF VARIANTSIn 2012, Symantec, using data from a command and control (C2) server of 5,700 computers compromised in one day, estimated that approximately 2.9 percent of those compromised users paid the ransom. With an average ransom of $200, this meant malicious actors profited $33,600 per day, or $394,400 per month, from a single C2 server. These rough estimates demonstrate how profitable ransomware can be for malicious actors. This financial success has likely led to a proliferation of ransomware variants. In 2013, more destructive and lucrative ransomware variants were introduced including Xorist, CryptorBit, and CryptoLocker. Some variants encrypt not just the files on the infected device but also the contents of shared or networked drives. These variants are considered destructive because they encrypt user’s and organization’s files, and render them useless until criminals receive a ransom. Additional variants observed in 2014 included CryptoDefense and Cryptowall, which are also considered destructive. Reports indicate that CryptoDefense and Cryptowall share the same code, and that only the name of malware itself is different. Similar to CryptoLocker, these variants also encrypt files on the local computer, shared network files, and removable media. LINKS TO OTHER TYPES OF MALWARESystems infected with ransomware are also often infected with other malware. In the case of CryptoLocker, a user typically becomes infected by opening a malicious attachment from an email. This malicious attachment contains Upatre, a downloader, which infects the user with GameOver Zeus. GameOver Zeus is a variant of the Zeus Trojan that steals banking information and is also used to steal other types of data. Once a system is infected with GameOver Zeus, Upatre will also download CryptoLocker. Finally, CryptoLocker encrypts files on the infected system, and requests that a ransom be paid. The close ties between ransomware and other types of malware were demonstrated through the recent botnet disruption operation against GameOver Zeus, which also proved effective against CryptoLocker. In June 2014, an international law enforcement operation successfully weakened the infrastructure of both GameOver Zeus and CryptoLocker. ImpactRansomware doesn’t only target home users; businesses can also become infected with ransomware, which can have negative consequences, including:
Paying the ransom does not guarantee the encrypted files will be released; it only guarantees that the malicious actors receive the victim’s money, and in some cases, their banking information. In addition, decrypting files does not mean the malware infection itself has been removed. SolutionInfections can be devastating to an individual or organization, and recovery can be a difficult process that may require the services of a reputable data recovery specialist. US-CERT and CCIRC recommend users and administrators take the following preventive measures to protect their computer networks from ransomware infection:
Individuals or organizations are not encouraged to pay the ransom, as this does not guarantee files will be released. Report instances of fraud to the FBI at the Internet Crime Complaint Center or contact the CCIRC . References
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