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2019-03-22
Ami, Or, Elovici, Yuval, Hendler, Danny.  2018.  Ransomware Prevention Using Application Authentication-Based File Access Control. Proceedings of the 33rd Annual ACM Symposium on Applied Computing. :1610-1619.

Ransomware emerged in recent years as one of the most significant cyber threats facing both individuals and organizations, inflicting global damage costs that are estimated upwards of $1 billion in 2016 alone [23]. The increase in the scale and impact of recent ransomware attacks highlights the need of finding effective countermeasures. We present AntiBotics - a novel system for application authentication-based file access control. AntiBotics enforces a file access-control policy by presenting periodic identification/authorization challenges.

We implemented AntiBotics for Windows. Our experimental evaluation shows that contemporary ransomware programs are unable to encrypt any of the files protected by AntiBotics and that the daily rate of challenges it presents to users is very low. We discuss possible ways in which future ransomware may attempt to attack AntiBotics and explain how these attacks can be thwarted.

2019-02-18
Takeuchi, Yuki, Sakai, Kazuya, Fukumoto, Satoshi.  2018.  Detecting Ransomware Using Support Vector Machines. Proceedings of the 47th International Conference on Parallel Processing Companion. :1:1–1:6.
Ransomeware is the most prevalent malicious software in 2017 that encrypts the files in a victim's machine and demands money, i.e., ransom, for decrypting the files. The global damage cost and financial losses of individuals and organizations due to ransomware is increasing year by year. Therefore, fighting against ransomware is an urgent issue. In this paper, we propose a ransomware detection scheme using support vector machines (SVMs), which is one of supervised machine learning algorithms. The key idea of the proposed scheme is to let a SVM learn the API calls of ransomware as its features so that the SVM detects unseen ransomware. Unlike the existing solutions, our scheme looks into the API call history in more detail. The testbeds using real 276 ransomware with San-box demonstrate that the proposed scheme improves the correct detection rate of ransomware.
2019-02-08
Lihet, M., Dadarlat, P. D. V..  2018.  Honeypot in the Cloud Five Years of Data Analysis. 2018 17th RoEduNet Conference: Networking in Education and Research (RoEduNet). :1-6.

The current paper is a continuation of a published article and is about the results of implementing a Honeypot in the Cloud. A five years period of raw data is analyzed and explained in the current Cyber Security state and landscape.

2019-01-16
Turaev, H., Zavarsky, P., Swar, B..  2018.  Prevention of Ransomware Execution in Enterprise Environment on Windows OS: Assessment of Application Whitelisting Solutions. 2018 1st International Conference on Data Intelligence and Security (ICDIS). :110–118.

Application whitelisting software allows only examined and trusted applications to run on user's machine. Since many malicious files don't require administrative privileges in order for them to be executed, whitelisting can be the only way to block the execution of unauthorized applications in enterprise environment and thus prevent infection or data breach. In order to assess the current state of such solutions, the access to three whitelisting solution licenses was obtained with the purpose to test their effectiveness against different modern types of ransomware found in the wild. To conduct this study a virtual environment was used with Windows Server and Enterprise editions installed. The objective of this paper is not to evaluate each vendor or make recommendations of purchasing specific software but rather to assess the ability of application control solutions to block execution of ransomware files, as well as assess the potential for future research. The results of the research show the promise and effectiveness of whitelisting solutions.

2018-05-24
Kim, H., Yoo, D., Kang, J. S., Yeom, Y..  2017.  Dynamic Ransomware Protection Using Deterministic Random Bit Generator. 2017 IEEE Conference on Application, Information and Network Security (AINS). :64–68.

Ransomware has become a very significant cyber threat. The basic idea of ransomware was presented in the form of a cryptovirus in 1995. However, it was considered as merely a conceptual topic since then for over a decade. In 2017, ransomware has become a reality, with several famous cases of ransomware having compromised important computer systems worldwide. For example, the damage caused by CryptoLocker and WannaCry is huge, as well as global. They encrypt victims' files and require user's payment to decrypt them. Because they utilize public key cryptography, the key for recovery cannot be found in the footprint of the ransomware on the victim's system. Therefore, once infected, the system cannot be recovered without paying for restoration. Various methods to deal this threat have been developed by antivirus researchers and experts in network security. However, it is believed that cryptographic defense is infeasible because recovering a victim's files is computationally as difficult as breaking a public key cryptosystem. Quite recently, various approaches to protect the crypto-API of an OS from malicious codes have been proposed. Most ransomware generate encryption keys using the random number generation service provided by the victim's OS. Thus, if a user can control all random numbers generated by the system, then he/she can recover the random numbers used by the ransomware for the encryption key. In this paper, we propose a dynamic ransomware protection method that replaces the random number generator of the OS with a user-defined generator. As the proposed method causes the virus program to generate keys based on the output from the user-defined generator, it is possible to recover an infected file system by reproducing the keys the attacker used to perform the encryption.

2018-05-09
Hasan, M. M., Rahman, M. M..  2017.  RansHunt: A Support Vector Machines Based Ransomware Analysis Framework with Integrated Feature Set. 2017 20th International Conference of Computer and Information Technology (ICCIT). :1–7.

Ransomware is one of the most increasing malwares used by cyber-criminals in recent days. This type of malware uses cryptographic technology that encrypts a user's important files, folders makes the computer systems unusable, holds the decryption key and asks for the ransom from the victims for recovery. The recent ransomware families are very sophisticated and difficult to analyze & detect using static features only. On the other hand, latest crypto-ransomwares having sandboxing and IDS evading capabilities. So obviously, static or dynamic analysis of the ransomware alone cannot provide better solution. In this paper, we will present a Machine Learning based approach which will use integrated method, a combination of static and dynamic analysis to detect ransomware. The experimental test samples were taken from almost all ransomware families including the most recent ``WannaCry''. The results also suggest that combined analysis can detect ransomware with better accuracy compared to individual analysis approach. Since ransomware samples show some ``run-time'' and ``static code'' features, it also helps for the early detection of new and similar ransomware variants.

2018-03-05
Kohlbrenner, Anne, Araujo, Frederico, Taylor, Teryl, Stoecklin, Marc Ph..  2017.  POSTER: Hidden in Plain Sight: A Filesystem for Data Integrity and Confidentiality. Proceedings of the 2017 ACM SIGSAC Conference on Computer and Communications Security. :2523–2525.

A filesystem capable of curtailing data theft and ensuring file integrity protection through deception is introduced and evaluated. The deceptive filesystem transparently creates multiple levels of stacking to protect the base filesystem and monitor file accesses, hide and redact sensitive files with baits, and inject decoys onto fake system views purveyed to untrusted subjects, all while maintaining a pristine state to legitimate processes. Our prototype implementation leverages a kernel hot-patch to seamlessly integrate the new filesystem module into live and existing environments. We demonstrate the utility of our approach with a use case on the nefarious Erebus ransomware. We also show that the filesystem adds no I/O overhead for legitimate users.

Chen, Zhi-Guo, Kang, Ho-Seok, Yin, Shang-Nan, Kim, Sung-Ryul.  2017.  Automatic Ransomware Detection and Analysis Based on Dynamic API Calls Flow Graph. Proceedings of the International Conference on Research in Adaptive and Convergent Systems. :196–201.

In recent cyber incidents, Ransom software (ransomware) causes a major threat to the security of computer systems. Consequently, ransomware detection has become a hot topic in computer security. Unfortunately, current signature-based and static detection model is often easily evadable by obfuscation, polymorphism, compress, and encryption. For overcoming the lack of signature-based and static ransomware detection approach, we have proposed the dynamic ransomware detection system using data mining techniques such as Random Forest (RF), Support Vector Machine (SVM), Simple Logistic (SL) and Naive Bayes (NB) algorithms for detecting known and unknown ransomware. We monitor the actual (dynamic) behaviors of software to generate API calls flow graphs (CFG) and transfer it in a feature space. Thereafter, data normalization and feature selection were applied to select informative features which are the best for discriminating between various categories of software and benign software. Finally, the data mining algorithms were used for building the detection model for judging whether the software is benign software or ransomware. Our experimental results show that our proposed system can be more effective to improve the performance for ransomware detection. Especially, the accuracy and detection rate of our proposed system with Simple Logistic (SL) algorithm can achieve to 98.2% and 97.6%, respectively. Meanwhile, the false positive rate also can be reduced to 1.2%.

Lee, Jeonghwan, Lee, Jinwoo, Hong, Jiman.  2017.  How to Make Efficient Decoy Files for Ransomware Detection? Proceedings of the International Conference on Research in Adaptive and Convergent Systems. :208–212.

Recently, Ransomware has been rapidly increasing and is becoming far more dangerous than other common malware types. Unlike previous versions of Ransomware that infect email attachments or access certain sites, the new Ransomware, such as WannaCryptor, corrupts data even when the PC is connected to the Internet. Therefore, many studies are being conducted to detect and defend Ransomware. However, existing studies on Ransomware detection cannot effectively detect and defend the new Ransomware because it detects Ransomware using signature databases or monitoring specific activities of processes. In this paper, we propose a method to make decoy files for detecting Ransomwares efficiently. The proposed method is based on the analysis of the behaviors of existing Ransomwares at the source code level.

Dion, Yap L., Joshua, Abigail A., Brohi, Sarfraz N..  2017.  Negation of Ransomware via Gamification and Enforcement of Standards. Proceedings of the 2017 International Conference on Computer Science and Artificial Intelligence. :203–208.

With the continued advancement of the internet and relevant programs, the number of exploitable loopholes in security systems increases. One such exploit that is plaguing the software scene is ransomware, a type of malware that weaves its way through these security loopholes and denies access to intellectual property and documents via encryption. The culprits will then demand a ransom as a price for data decryption. Many businesses face the issue of not having stringent security measures that are sufficient enough to negate the threat of ransomware. This jeopardizes the availability of sensitive data as corporations and individuals are at threat of losing data crucial to business or personal operations. Although certain countermeasures to deal with ransomware exist, the fact that a plethora of new ransomware cases keeps appearing every year points to the problem that they aren't effective enough. This paper aims to conceptualize practical solutions that can be used as foundations to build on in hope that more effective and proactive countermeasures to ransomware can be developed in the future.

Pradhan, A., Marimuthu, K., Niranchana, R., Vijayakumar, P..  2017.  Secure Protocol for Subscriber Identity Module. 2017 Second International Conference on Recent Trends and Challenges in Computational Models (ICRTCCM). :358–362.

Subscriber Identity Module (SIM) is the backbone of modern mobile communication. SIM can be used to store a number of user sensitive information such as user contacts, SMS, banking information (some banking applications store user credentials on the SIM) etc. Unfortunately, the current SIM model has a major weakness. When the mobile device is lost, an adversary can simply steal a user's SIM and use it. He/she can then extract the user's sensitive information stored on the SIM. Moreover, The adversary can then pose as the user and communicate with the contacts stored on the SIM. This opens up the avenue to a large number of social engineering techniques. Additionally, if the user has provided his/her number as a recovery option for some accounts, the adversary can get access to them. The current methodology to deal with a stolen SIM is to contact your particular service provider and report a theft. The service provider then blocks the services on your SIM, but the adversary still has access to the data which is stored on the SIM. Therefore, a secure scheme is required to ensure that only legal users are able to access and utilize their SIM.

Yin, H. Sun, Vatrapu, R..  2017.  A First Estimation of the Proportion of Cybercriminal Entities in the Bitcoin Ecosystem Using Supervised Machine Learning. 2017 IEEE International Conference on Big Data (Big Data). :3690–3699.

Bitcoin, a peer-to-peer payment system and digital currency, is often involved in illicit activities such as scamming, ransomware attacks, illegal goods trading, and thievery. At the time of writing, the Bitcoin ecosystem has not yet been mapped and as such there is no estimate of the share of illicit activities. This paper provides the first estimation of the portion of cyber-criminal entities in the Bitcoin ecosystem. Our dataset consists of 854 observations categorised into 12 classes (out of which 5 are cybercrime-related) and a total of 100,000 uncategorised observations. The dataset was obtained from the data provider who applied three types of clustering of Bitcoin transactions to categorise entities: co-spend, intelligence-based, and behaviour-based. Thirteen supervised learning classifiers were then tested, of which four prevailed with a cross-validation accuracy of 77.38%, 76.47%, 78.46%, 80.76% respectively. From the top four classifiers, Bagging and Gradient Boosting classifiers were selected based on their weighted average and per class precision on the cybercrime-related categories. Both models were used to classify 100,000 uncategorised entities, showing that the share of cybercrime-related is 29.81% according to Bagging, and 10.95% according to Gradient Boosting with number of entities as the metric. With regard to the number of addresses and current coins held by this type of entities, the results are: 5.79% and 10.02% according to Bagging; and 3.16% and 1.45% according to Gradient Boosting.

Zimba, A., Wang, Z., Chen, H..  2017.  Reasoning Crypto Ransomware Infection Vectors with Bayesian Networks. 2017 IEEE International Conference on Intelligence and Security Informatics (ISI). :149–151.

Ransomware techniques have evolved over time with the most resilient attacks making data recovery practically impossible. This has driven countermeasures to shift towards recovery against prevention but in this paper, we model ransomware attacks from an infection vector point of view. We follow the basic infection chain of crypto ransomware and use Bayesian network statistics to infer some of the most common ransomware infection vectors. We also employ the use of attack and sensor nodes to capture uncertainty in the Bayesian network.

Gonzalez, D., Hayajneh, T..  2017.  Detection and Prevention of Crypto-Ransomware. 2017 IEEE 8th Annual Ubiquitous Computing, Electronics and Mobile Communication Conference (UEMCON). :472–478.

Crypto-ransomware is a challenging threat that ciphers a user's files while hiding the decryption key until a ransom is paid by the victim. This type of malware is a lucrative business for cybercriminals, generating millions of dollars annually. The spread of ransomware is increasing as traditional detection-based protection, such as antivirus and anti-malware, has proven ineffective at preventing attacks. Additionally, this form of malware is incorporating advanced encryption algorithms and expanding the number of file types it targets. Cybercriminals have found a lucrative market and no one is safe from being the next victim. Encrypting ransomware targets business small and large as well as the regular home user. This paper discusses ransomware methods of infection, technology behind it and what can be done to help prevent becoming the next victim. The paper investigates the most common types of crypto-ransomware, various payload methods of infection, typical behavior of crypto ransomware, its tactics, how an attack is ordinarily carried out, what files are most commonly targeted on a victim's computer, and recommendations for prevention and safeguards are listed as well.

Chen, Q., Bridges, R. A..  2017.  Automated Behavioral Analysis of Malware: A Case Study of WannaCry Ransomware. 2017 16th IEEE International Conference on Machine Learning and Applications (ICMLA). :454–460.

Ransomware, a class of self-propagating malware that uses encryption to hold the victims' data ransom, has emerged in recent years as one of the most dangerous cyber threats, with widespread damage; e.g., zero-day ransomware WannaCry has caused world-wide catastrophe, from knocking U.K. National Health Service hospitals offline to shutting down a Honda Motor Company in Japan [1]. Our close collaboration with security operations of large enterprises reveals that defense against ransomware relies on tedious analysis from high-volume systems logs of the first few infections. Sandbox analysis of freshly captured malware is also commonplace in operation. We introduce a method to identify and rank the most discriminating ransomware features from a set of ambient (non-attack) system logs and at least one log stream containing both ambient and ransomware behavior. These ranked features reveal a set of malware actions that are produced automatically from system logs, and can help automate tedious manual analysis. We test our approach using WannaCry and two polymorphic samples by producing logs with Cuckoo Sandbox during both ambient, and ambient plus ransomware executions. Our goal is to extract the features of the malware from the logs with only knowledge that malware was present. We compare outputs with a detailed analysis of WannaCry allowing validation of the algorithm's feature extraction and provide analysis of the method's robustness to variations of input data—changing quality/quantity of ambient data and testing polymorphic ransomware. Most notably, our patterns are accurate and unwavering when generated from polymorphic WannaCry copies, on which 63 (of 63 tested) antivirus (AV) products fail.

Subedi, K. P., Budhathoki, D. R., Chen, B., Dasgupta, D..  2017.  RDS3: Ransomware Defense Strategy by Using Stealthily Spare Space. 2017 IEEE Symposium Series on Computational Intelligence (SSCI). :1–8.

Ransomware attacks are becoming prevalent nowadays with the flourishing of crypto-currencies. As the most harmful variant of ransomware crypto-ransomware encrypts the victim's valuable data, and asks for ransom money. Paying the ransom money, however, may not guarantee recovery of the data being encrypted. Most of the existing work for ransomware defense purely focuses on ransomware detection. A few of them consider data recovery from ransomware attacks, but they are not able to defend against ransomware which can obtain a high system privilege. In this work, we design RDS3, a novel Ransomware Defense Strategy, in which we Stealthily back up data in the Spare space of a computing device, such that the data encrypted by ransomware can be restored. Our key idea is that the spare space which stores the backup data is fully isolated from the ransomware. In this way, the ransomware is not able to ``touch'' the backup data regardless of what privilege it can obtain. Security analysis and experimental evaluation show that RDS3 can mitigate ransomware attacks with an acceptable overhead.

2018-02-21
Yalew, S. Demesie, Maguire, G. Q., Haridi, S., Correia, M..  2017.  Hail to the Thief: Protecting data from mobile ransomware with ransomsafedroid. 2017 IEEE 16th International Symposium on Network Computing and Applications (NCA). :1–8.

The growing popularity of Android and the increasing amount of sensitive data stored in mobile devices have lead to the dissemination of Android ransomware. Ransomware is a class of malware that makes data inaccessible by blocking access to the device or, more frequently, by encrypting the data; to recover the data, the user has to pay a ransom to the attacker. A solution for this problem is to backup the data. Although backup tools are available for Android, these tools may be compromised or blocked by the ransomware itself. This paper presents the design and implementation of RANSOMSAFEDROID, a TrustZone based backup service for mobile devices. RANSOMSAFEDROID is protected from malware by leveraging the ARM TrustZone extension and running in the secure world. It does backup of files periodically to a secure local persistent partition and pushes these backups to external storage to protect them from ransomware. Initially, RANSOMSAFEDROID does a full backup of the device filesystem, then it does incremental backups that save the changes since the last backup. As a proof-of-concept, we implemented a RANSOMSAFEDROID prototype and provide a performance evaluation using an i.MX53 development board.

2018-02-15
Kuzuno, H., Karam, C..  2017.  Blockchain explorer: An analytical process and investigation environment for bitcoin. 2017 APWG Symposium on Electronic Crime Research (eCrime). :9–16.

Bitcoin is the most famous cryptocurrency currently operating with a total marketcap of almost 7 billion USD. This innovation stands strong on the feature of pseudo anonymity and strives on its innovative de-centralized architecture based on the Blockchain. The Blockchain is a distributed ledger that keeps a public record of all the transactions processed on the bitcoin protocol network in full transparency without revealing the identity of the sender and the receiver. Over the course of 2016, cryptocurrencies have shown some instances of abuse by criminals in their activities due to its interesting nature. Darknet marketplaces are increasing the volume of their businesses in illicit and illegal trades but also cryptocurrencies have been used in cases of extortion, ransom and as part of sophisticated malware modus operandi. We tackle these challenges by developing an analytical capability that allows us to map relationships on the blockchain and filter crime instances in order to investigate the abuse in law enforcement local environment. We propose a practical bitcoin analytical process and an analyzing system that stands alone and manages all data on the blockchain in real-time with tracing and visualizing techniques rendering transactions decipherable and useful for law enforcement investigation and training. Our system adopts combination of analyzing methods that provides statistics of address, graphical transaction relation, discovery of paths and clustering of already known addresses. We evaluated our system in the three criminal cases includes marketplace, ransomware and DDoS extortion. These are practical training in law enforcement, then we determined whether our system could help investigation process and training.

Han, Jordan W., Hoe, Ong J., Wing, Joseph S., Brohi, Sarfraz N..  2017.  A Conceptual Security Approach with Awareness Strategy and Implementation Policy to Eliminate Ransomware. Proceedings of the 2017 International Conference on Computer Science and Artificial Intelligence. :222–226.

Undeterred by numerous efforts deployed by antivirus software that shields users from various security threats, ransomware is constantly evolving as technology advances. The impact includes hackers hindering the user's accessibility to their data, and the user will pay ransom to retrieve their data. Ransomware also targets multimillion-dollar organizations, and it can cause colossal data loss. The organizations could face catastrophic consequences, and business operations could be ceased. This research contributes by spreading awareness of ransomware to alert people to tackle ransomware. The solution of this research is the conceptual development of a browser extension that provides assistance to warn users of plausible dangers while surfing the Internet. It allows the users to surf the web safely. Since the contribution of this research is conceptual, we can assume that technology users will adopt the proposed idea to prevent ransomware attacks on their personal computers once the solution is fully implemented in future research.

2018-02-06
Bhattacharya, S., Kumar, C. R. S..  2017.  Ransomware: The CryptoVirus Subverting Cloud Security. 2017 International Conference on Algorithms, Methodology, Models and Applications in Emerging Technologies (ICAMMAET). :1–6.

Cloud computing presents unlimited prospects for Information Technology (IT) industry and business enterprises alike. Rapid advancement brings a dark underbelly of new vulnerabilities and challenges unfolding with alarming regularity. Although cloud technology provides a ubiquitous environment facilitating business enterprises to conduct business across disparate locations, security effectiveness of this platform interspersed with threats which can bring everything that subscribes to the cloud, to a halt raises questions. However advantages of cloud platforms far outweighs drawbacks and study of new challenges helps overcome drawbacks of this technology. One such emerging security threat is of ransomware attack on the cloud which threatens to hold systems and data on cloud network to ransom with widespread damaging implications. This provides huge scope for IT security specialists to sharpen their skillset to overcome this new challenge. This paper covers the broad cloud architecture, current inherent cloud threat mechanisms, ransomware vulnerabilities posed and suggested methods to mitigate it.

2017-12-12
Zahra, A., Shah, M. A..  2017.  IoT based ransomware growth rate evaluation and detection using command and control blacklisting. 2017 23rd International Conference on Automation and Computing (ICAC). :1–6.

Internet of things (IoT) is internetworking of various physical devices to provide a range of services and applications. IoT is a rapidly growing field, on an account of this; the security measurements for IoT should be at first concern. In the modern day world, the most emerging cyber-attack threat for IoT is ransomware attack. Ransomware is a kind of malware with the aim of rendering a victim's computer unusable or inaccessible, and then asking the user to pay a ransom to revert the destruction. In this paper we are evaluating ransomware attacks statistics for the past 2 years and the present year to estimate growth rate of the most emerging ransomware families from the last 3 years to evaluate most threatening ransomware attacks for IoT. Growth rate results shows that the number of attacks for Cryptowall and locky ransomware are notably increasing therefore, these ransomware families are potential threat to IoT. Moreover, we present a Cryptowall ransomware attack detection model based on the communication and behavioral study of Cryptowall for IoT environment. The proposed model observes incoming TCP/IP traffic through web proxy server then extracts TCP/IP header and uses command and control (C&C) server black listing to detect ransomware attacks.

2017-11-03
Dietrich, Christian J., Rossow, Christian, Pohlmann, Norbert.  2013.  Exploiting Visual Appearance to Cluster and Detect Rogue Software. Proceedings of the 28th Annual ACM Symposium on Applied Computing. :1776–1783.

Rogue software, such as Fake A/V and ransomware, trick users into paying without giving return. We show that using a perceptual hash function and hierarchical clustering, more than 213,671 screenshots of executed malware samples can be grouped into subsets of structurally similar images, reflecting image clusters of one malware family or campaign. Based on the clustering results, we show that ransomware campaigns favor prepay payment methods such as ukash, paysafecard and moneypak, while Fake A/V campaigns use credit cards for payment. Furthermore, especially given the low A/V detection rates of current rogue software – sometimes even as low as 11% – our screenshot analysis approach could serve as a complementary last line of defense.

Kolodenker, Eugene, Koch, William, Stringhini, Gianluca, Egele, Manuel.  2017.  PayBreak: Defense Against Cryptographic Ransomware. Proceedings of the 2017 ACM on Asia Conference on Computer and Communications Security. :599–611.

Similar to criminals in the physical world, cyber-criminals use a variety of illegal and immoral means to achieve monetary gains. Recently, malware known as ransomware started to leverage strong cryptographic primitives to hold victims' computer files "hostage" until a ransom is paid. Victims, with no way to defend themselves, are often advised to simply pay. Existing defenses against ransomware rely on ad-hoc mitigations that target the incorrect use of cryptography rather than generic live protection. To fill this gap in the defender's arsenal, we describe the approach, prototype implementation, and evaluation of a novel, automated, and most importantly proactive defense mechanism against ransomware. Our prototype, called PayBreak, effectively combats ransomware, and keeps victims' files safe. PayBreak is based on the insight that secure file encryption relies on hybrid encryption where symmetric session keys are used on the victim computer. PayBreak observes the use of these keys, holds them in escrow, and thus, can decrypt files that would otherwise only be recoverable by paying the ransom. Our prototype leverages low overhead dynamic hooking techniques and asymmetric encryption to realize the key escrow mechanism which allows victims to restore the files encrypted by ransomware. We evaluated PayBreak for its effectiveness against twenty hugely successful families of real-world ransomware, and demonstrate that our system can restore all files that are encrypted by samples from twelve of these families, including the infamous CryptoLocker, and more recent threats such as Locky and SamSam. Finally, PayBreak performs its protection task at negligible performance overhead for common office workloads and is thus ideally suited as a proactive online protection system.

Liao, K., Zhao, Z., Doupe, A., Ahn, G. J..  2016.  Behind closed doors: measurement and analysis of CryptoLocker ransoms in Bitcoin. 2016 APWG Symposium on Electronic Crime Research (eCrime). :1–13.

Bitcoin, a decentralized cryptographic currency that has experienced proliferating popularity over the past few years, is the common denominator in a wide variety of cybercrime. We perform a measurement analysis of CryptoLocker, a family of ransomware that encrypts a victim's files until a ransom is paid, within the Bitcoin ecosystem from September 5, 2013 through January 31, 2014. Using information collected from online fora, such as reddit and BitcoinTalk, as an initial starting point, we generate a cluster of 968 Bitcoin addresses belonging to CryptoLocker. We provide a lower bound for CryptoLocker's economy in Bitcoin and identify 795 ransom payments totalling 1,128.40 BTC (\$310,472.38), but show that the proceeds could have been worth upwards of \$1.1 million at peak valuation. By analyzing ransom payment timestamps both longitudinally across CryptoLocker's operating period and transversely across times of day, we detect changes in distributions and form conjectures on CryptoLocker that corroborate information from previous efforts. Additionally, we construct a network topology to detail CryptoLocker's financial infrastructure and obtain auxiliary information on the CryptoLocker operation. Most notably, we find evidence that suggests connections to popular Bitcoin services, such as Bitcoin Fog and BTC-e, and subtle links to other cybercrimes surrounding Bitcoin, such as the Sheep Marketplace scam of 2013. We use our study to underscore the value of measurement analyses and threat intelligence in understanding the erratic cybercrime landscape.

Ahmadian, M. M., Shahriari, H. R..  2016.  2entFOX: A framework for high survivable ransomwares detection. 2016 13th International Iranian Society of Cryptology Conference on Information Security and Cryptology (ISCISC). :79–84.

Ransomwares have become a growing threat since 2012, and the situation continues to worsen until now. The lack of security mechanisms and security awareness are pushing the systems into mire of ransomware attacks. In this paper, a new framework called 2entFOX' is proposed in order to detect high survivable ransomwares (HSR). To our knowledge this framework can be considered as one of the first frameworks in ransomware detection because of little publicly-available research in this field. We analyzed Windows ransomwares' behaviour and we tried to find appropriate features which are particular useful in detecting this type of malwares with high detection accuracy and low false positive rate. After hard experimental analysis we extracted 20 effective features which due to two highly efficient ones we could achieve an appropriate set for HSRs detection. After proposing architecture based on Bayesian belief network, the final evaluation is done on some known ransomware samples and unknown ones based on six different scenarios. The result of this evaluations shows the high accuracy of 2entFox in detection of HSRs.