I have a machine that is obviously infected, and when I ran MalwareBytes it told me that it found some "malicious" registry keys (surprisingly enough these contained file path to currently non-existent javascript files). But, that's it. Full scan did not uncover any malicious files, or malicious hidden processes in memory. Like, maybe the (hidden?) process that for whatever reason periodically injects keystrokes (hotkeys?) into whatever currently open window.
Windows Registry Infecting Malware Has NO Files
It might be the case that another program (like your antivirus, CCleaner, or some other anti-malware app you've used) already deleted the files but left the Registry keys behind. It might also be the case that the malware relocated itself one or more times while trying to evade detection, or created decoy registry keys.
When security researchers talk about malware, they usually refer to files stored on a computer system, which intends to damage a device or steal sensitive data from it. Those files can be scanned by AV engines and can be handled in a classic way. The following analysis is an example of malware which resides in the registry only, is persistent and is not present as a file which can be scanned easily.
The G DATA SecurityLabs have analyzed persistent malware which resides in the registry only and therefore does not create any file on the infected system. An overview of this mechanism was firstly described quite recently in the KernelMode.info forum. The analyzed sample is dropped by a Microsoft Word document which exploits the vulnerability described in CVE-2012-0158. The document was reported to be found as an attachment of fake Canada Post and/or USPS email which claims to hold information about ordered items for the recipient of the spam.
Another common method used by malware is to hijack a concept about how the OS loads DLLs. Whenever an exe loads (even explorer.exe), it follows a certain path search to load the required DLLs. Because DLLs are loaded in the order the directories are parsed, it is possible to add a malicious DLL with the same name in a directory earlier than the directory where the legit DLL resides. If Safe DLL search mode is enabled (which is by default on most versions) then OS will check whether the DLL is already loaded in memory or is it a part of Known DLLs registry key located at HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession ManagerKnownDLLs. If OS cannot find the DLL at either of these, then DLL search starts in the following order
While these three core steps exist in all ransomware variants, different ransomware can include different implementations or additional steps. For example, ransomware variants like Maze perform files scanning, registry information, and data theft before data encryption, and the WannaCry ransomware scans for other vulnerable devices to infect and encrypt.
The text "DoesNotExist" in the third line is meant to be a place in the registry that does not exist. If this zap gets very popular, malware may look for it, so it can't hurt to change it just a bit. For example, I might use something like
The look and feel of browsing the registry with regedit is very much like browsing files and folders with Windows Explorer. You delete a subkey in the registry by right clicking on it and selecting Delete from the popup menu.
The entire operational system of antimalware programs is based on checking files. So, the move to a fileless system was a very clever move by hackers that has blindsided traditional antivirus procedures. Although antivirus producers have problems reimagining their strategies, Microsoft showed no hesitation at throwing resources at the problem and has contributed to a reduction of attack successes on Windows computers.
An increase in the outgoing web traffic is the general indication of an infection; this applies to both individual computers and corporate networks. If no users are working in the Internet in a specific time period (e.g. at night), but the web traffic continues, this could mean that somebody or someone else is active on the system, and most probably that is a malicious activity. In a firewall is configured in the system, attempts by unknown applications to establish Internet connections may be indicative of an infection. Numerous advertisement windows popping up while visiting web-sites may signal that an adware in present in the system. If a computer freezes or crashes frequently, this may be also related to a malware activity. Such malfunctions are more often accounted for by hardware or software malfunctions rather than a virus activity. However, if similar symptoms simultaneously occur on multiple or numerous computers on the network, accompanied by a dramatic increase in the internal traffic, this is very likely caused by a network worm or a backdoor Trojan spreading across the network.
One of the most dangerous and innocuous spots highly sophisticated malware can hide is your critical system files. Traditionally, many malware files that were used to replace or modify existing critical system files were distinguished by a foreign signature or metadata that is visible in the attribute certifiable field (ACT) of signed files.
One of the difficulties in manually auditing your Windows registry keys to detect abnormalities can be a massive undertaking. It would theoretically require the comparison of log files to the tens of thousands of autorun settings. While there are some possible shortcuts, efficiently determining modifications to your registry keys is typically best achieved with an effective file integrity monitoring solution.
Both malware and ransomware can gain hold within a system after download with cleverly-disguised .lnk files that may resemble an existing shortcut or even an innocuous PDF document. Unfortunately, the average end-user cannot tell the difference since the .lnk aspect of the file isn't visibly displayed.
Malwarebytes is an example of an antimalware tool that handles detection and removal of malware. It can remove malware from Windows, macOS, Android and iOS platforms. Malwarebytes can scan a user's registry files, running programs, hard drives and individual files. If detected, malware can then be quarantined and deleted. However, unlike some other tools, users cannot set automatic scanning schedules.
A few years ago, ransomware was primarily a consumer problem. However, cybercriminals behind recent ransomware attacks have now shifted their focus to businesses. One example of this is ransomware families such as Ryuk, which is commonly used to target enterprise environments. Users in these enterprises are typically targeted with phishing emails containing Microsoft Office document files with embedded malicious macro code. In another example, RobbinHood ransomware uses a vulnerable Windows kernel driver that is included along with the malware. This vulnerability is then used to install the malware on the host system.
Monitor for an attempt by a user to gain access to a network or computing resource, often by providing credentials that may delete or alter generated artifacts on a host system, including logs or captured files such as quarantined malware.
The malware updates %CD% to the path of the running module and sets HKLM\Software\WanaCrypt0r\wd to %CD%. The malware then loads the XIA resource and decompresses numerous files (see Table 3) to %CD%. The malware then opens %CD%\c.wnry (the configuration data) and loads it into memory. It expects the file to be of size 0x30C. The malware then chooses randomly between the three strings 13AM4VW2dhxYgXeQepoHkHSQuy6NgaEb94, 12t9YDPgwueZ9NyMgw519p7AA8isjr6SMw, and 115p7UMMngoj1pMvkpHijcRdfJNXj6LrLn; writes it to offset 0xB2 in the configuration file; and writes the updated configuration data back to %CD%\c.wnry.
A registry key name starting with 8 to 15 characters between 'a' and 'z' followed by three random values between '0' and '9' is then generated by the malware. It may then create the following registry paths with the generated key name:
The malware then targets files on the user's desktop and documents folders. When the malware starts scanning a directory it creates a temporary file with the prefix "SD", and deletes it if successful.
When selecting which files to encrypt, the malware skips over files with .exe, .dll, and .wncry extensions. The files with the extensions shown in Figure 7 are selected for encryption. Files larger than 209,715,200 bytes may also be encrypted.
The files are encrypted with a randomly generated 128-bit AES key in CBC mode with a NULL initialization vector. The key is generated per file, is encrypted with the generated RSA public key, and included in the encrypted file header. Each file encrypted by the malware starts with the string WANACRY! and has the WNCRY extension. Depending on the file properties, the malware may also stage files in a WNCRYT extension.
When encrypting the AES key with RSA, the malware may use the embedded RSA key or a key randomly generated. If the file f.wnry does not exist during initilazation, the malware generates a random number if the file size is less than 209,715,200 bytes. If the number is a multiple of 100, the malware uses the embedded RSA key to encrypt the AES key. A maximum of ten files can be encrypted with this key. When an AES key is encrypted with this RSA key, the malware writes the file path to the file f.wnry. If the random number is not a multiple of 100 or the file f.wnry already exists on the system, the malware will encrypt the AES key with the randomly generated RSA key.
The malware communicates with an Onion server using a Tor server running on local host TCP port 9050. The malware registers the system with the Onion server, transferring encryption keys and deleting volume shadows. Once the ransom is paid, the malware obtains the decrypted RSA private key from the Onion server and decrypts ransomed files.
It first attempts to read the contents of the registry path HKLM\Software\WanaCrypt0r\wd. If this fails, the malware attempts to read the contents from a similar registry path within the HKCU registry hive. If one of the registry paths exists, the malware sets the current directory to value read from the registry. 2ff7e9595c
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