132 lines
9.4 KiB
JSON
132 lines
9.4 KiB
JSON
{
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"namespace": "ransomware",
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"expanded": "ransomware types and elements",
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"description": "Ransomware is used to define ransomware types and the elements that compose them.",
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"version": 1,
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"refs": [
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"https://www.symantec.com/content/en/us/enterprise/media/security_response/whitepapers/the-evolution-of-ransomware.pdf"
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],
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"predicates": [
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{
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"value": "type",
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"expanded": "Type",
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"description": "Type is used to describe the type of a ransomware and how it works."
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},
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{
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"value": "element",
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"expanded": "Element",
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"description": "Elements that composed or are linked to a ransomware and its execution."
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},
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{
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"value": "complexity-level",
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"expanded": "Complexity level",
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"description": "Level of complexity of the ransomware."
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}
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],
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"values": [
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{
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"predicate": "type",
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"entry": [
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{
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"value": "scareware",
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"expanded": "Scareware is a form of malware which uses social engineering to cause shock, anxiety, or the perception of a threat in order to manipulate users into buying unwanted software."
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},
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{
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"value": "locker-ransomware",
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"expanded": "Locker eansomware, also called computer locker, denies access to the computer or device "
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},
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{
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"value": "crypto-ransomware",
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"expanded": "Crypto ransomware, also called data locker prevents access to files or data. Crypto ransomware doesn’t necessarily have to use encryption to stop users from accessing their data, but the vast majority of it does."
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}
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]
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},
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{
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"predicate": "element",
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"entry": [
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{
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"value": "ransomnote",
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"expanded": "A ransomnote is the message left by the attacker to threaten his victim and ask for ransom. It is usually seen as a text file or a picture set as background."
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},
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{
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"value": "dropper",
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"expanded": "A dropper is a means of getting malware into a machine while bypassing the security checks by carring the malware inside of itself."
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},
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{
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"value": "downloader",
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"expanded": "a downloader is a means of getting malware into a machine while bypassing the security checks, by downloading it instead of carring it."
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}
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]
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},
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{
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"predicate": "complexity-level",
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"entry": [
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{
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"value": "no-actual-encryption-fake-scareware",
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"expanded": "No actual encryption (fake scareware). infection merely poses as a ransomware by displaying a ransom note while not actually encrypting user files"
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},
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{
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"value": "display-ransomnote-before-encrypting",
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"expanded": "Displaying the ransom note before encryption process commences. As seen in the case of Nemucod, some ransomware will display a ransom note before file encryption. This is a serious operational flaw in the ransomware. The victim or their antivirus solution could effectively take prompt evasive action to prevent ransomware from commencing encryption."
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},
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{
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"value": "decryption-essentials-extracted-from-binary",
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"expanded": "Decryption essentials can be reverse engineered from ransomware code or the user system. For example, if the ransomware uses a hard-coded key, then it becomes straight-forward for malware analysts to extract the key by disassembling the ransomware binary. "
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},
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{
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"value": "derived-encryption-key-predicted ",
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"expanded": "Another possibility of reverse engineering the key is demonstrated in the case of the Linux.Encoder. Aransomware where a timestamp on the system was used to create keys for encryption resulting in easy decryption provided that the timestamp is still accessible."
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},
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{
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"value": "same-key used-for-each-infection",
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"expanded": "Ransomware uses the same key for every victim. If the same key is used to encrypt all victims during a campaign, then one victim can share the secret key with others."
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},
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{
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"value": "encryption-circumvented",
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"expanded": "decryption possible without key - Files can be decrypted without the need for a key due to poor choice or implementation of the encryption algorithm. Consider the case of desuCrypt that used an RC4 stream cipher for encryption. Using a stream cipher with key reuse is vulnerable to known plaintext attacks and known-ciphertext attacks due to the keyreuse vulnerability and hence this is a poor implementation of the encryption algorithm."
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},
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{
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"value": "file-restoration-possible-using-shadow-volume-copies",
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"expanded": "Files can be restored using system backups, e.g. Shadow Volume Copies on the New Technology File System (NTFS), that were neglected by the ransomware."
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},
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{
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"value": "key-recovered-from-file-system-or-memory",
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"expanded": "Decryption key can be retrieved from the host machine’s file structure or memory by an average user without the need for an expert. In the case of CryptoDefense, the ransomware did not securely delete keys from the host machine. The user can look in the right folder to discover the decryption key."
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},
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{
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"value": "due-diligence-prevented-ransomware-from-acquiring-key",
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"expanded": "User can prevent ransomware from acquiring the encryption key. Ransomware belongs in this category if its encryption procedure can be interrupted or blocked by due diligence on part of the user. For example, CryptoLocker discussed above cannot commence operation until it receives a key from the C&C server. A host or border firewall can block a list of known C&C servers hence rendering ransomware ineffective."
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},
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{
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"value": "click-and-run-decryptor-exists",
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"expanded": "Easy ‘Click-and-run’ solution such as a decryptor has been created by the security community such that a user can simply run the program to decrypt all files."
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},
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{
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"value": "kill-switch-exists-outside-of-attacker-s-control",
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"expanded": "There exists a kill switch outside of attacker’s control that renders the cryptoviral infection ineffective. For example, in the case of WannaCry, a global kill switch existed in the form of a domain name. The ransomware reached out to this domain before commencing encryption and if the domain existed, the ransomware aborted execution. This kill switch was outside the attacker’s control as anyone could register it and neutralize the ransomware outbreak."
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},
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{
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"value": "decryption-key-recovered-from-a-C&C-server-or-network-communications",
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"expanded": "Key can be retrieved from a central location such as a C&C server on a compromised host or gleaned with some difficulty from communication between ransomware on the host and the C&C server. For instance, in the case of CryptoLocker, authorities were able to seize a network of compromised hosts used to spread CryptoLocker and gain access to decryption essentials of around 500, 000 victims."
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},
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{
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"value": "custom-encryption-algorithm-used",
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"expanded": "Ransomware uses custom encryption techniques and violates the fundamental rule of cryptography: “do not roll your own crypto.” It is tempting to design a custom cipher that one cannot break themselves, however it will likely not withstand the scrutiny of professional cryptanalysts. Amateur custom cryptography in the ransomware implies there will likely soon be a solution to decrypt files without paying the ransom. An example of this is an early variant of the GPCoder ransomware that emerged in 2005 with weak custom encryption."
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},
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{
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"value": "decryption-key-recovered-under-specialized-lab-setting",
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"expanded": "Key can only be retrieved under rare, specialized laboratory settings. For example, in the case of WannaCry, a vulnerability in a cryptographic API on an unpatched Windows XP system allowed users to acquire from RAM the prime numbers used to compute private keys and hence retrieve the decryption key. However, the victim had to have been running a specific version of Windows XP and be fortunate enough that the related address space in memory has not been reallocated to another process. In another example, it is theoretically possible to reverse WannaCry encryption by exploiting a flaw in the pseudo-random-number-generator (PRNG) in an unpatched Windows XP system that reveals keys generated in the past. Naturally, these specialized conditions are not true for most victims."
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},
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{
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"value": "small-subset-of-files-left-unencrypted",
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"expanded": "A small subset of files left unencrypted by the ransomware for any number of reasons. Certain ransomware are known to only encrypt a file if its size exceeds a predetermined value. In addition, ransomware might decrypt a few files for free to prove decryption is possible. In such cases, a small number of victims may be lucky enough to only need these unencrypted files and can tolerate loss of the rest."
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},
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{
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"value": "encryption-model-is-seemingly-flawless",
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"expanded": "Encryption model is resistant to cryptographic attacks and has been implemented seemingly flawlessly such that there are no known vulnerabilities in its execution. Simply put, there is no proven way yet to decrypt the files without paying the ransom."
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}
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]
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}
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]
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}
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