Malware Families

According to Mandiant, STOWAWAY is a publicly available backdoor and proxy. The project supports several types of communication like SSH, socks5. Backdoor component supports upload and download of files, remote shell and basic information gathering.

First introduced in March 2024, ACR Stealer is an information stealer sold as a Malware-as-a-Service (MaaS) on Russian-speaking cybercrime forums by a threat actor named "SheldIO". Researchers posit that this malware is an evolved version of the GrMsk Stealer, which likely aligns with the private stealer that SheldIO has been selling since July 2023. The malware, written in C++, is compatible with Windows 7 through 10, and the seller manages all command and control (C2) infrastructure. ACR Stealer can harvest system information, stored credentials, web browser cookies, cryptocurrency wallets, and configuration files for various programs. Additionally, it employs the dead drop resolver (DDR) technique to obfuscate the actual C2 infrastructure.

aka Sodin, Sodinokibi

REvil Beta MD5: bed6fc04aeb785815744706239a1f243 SHA1: 3d0649b5f76dbbff9f86b926afbd18ae028946bf SHA256: 3641b09bf6eae22579d4fd5aae420476a134f5948966944189a70afd8032cb45 * Privilege escalation via CVE-2018-8453 (64-bit only) * Rerun with RunAs to elevate privileges * Implements a requirement that if "exp" is set, privilege escalation must be successful for full execution to occur * Implements target whitelisting using GetKetboardLayoutList * Contains debug console logging functionality * Defines the REvil registry root key as SOFTWARE\!test * Includes two variable placeholders in the ransom note: UID & KEY * Terminates processes specified in the "prc" configuration key prior to encryption * Deletes shadow copies and disables recovery * Wipes contents of folders specified in the "wfld" configuration key prior to encryption * Encrypts all non-whitelisted files on fixed drives * Encrypts all non-whitelisted files on network mapped drives if it is running with System-level privileges or can impersonate the security context of explorer.exe * Partially implements a background image setting to display a basic "Image text" message * Sends encrypted system data to a C2 domain via an HTTPS POST request (URI path building is not implemented.) ------------------------------------ REvil 1.00 MD5: 65aa793c000762174b2f86077bdafaea SHA1: 95a21e764ad0c98ea3d034d293aee5511e7c8457 SHA256: f0c60f62ef9ffc044d0b4aeb8cc26b971236f24a2611cb1be09ff4845c3841bc * Adds 32-bit implementation of CVE-2018-8453 exploit * Removes console debug logging * Changes the REvil registry root key to SOFTWARE\recfg * Removes the System/Impersonation success requirement for encrypting network mapped drives * Adds a "wipe" key to the configuration for optional folder wiping * Fully implements the background image setting and leverages values defined in the "img" configuration key * Adds an EXT variable placeholder to the ransom note to support UID, KEY, and EXT * Implements URI path building so encrypted system data is sent to a C2 pseudo-random URL * Fixes the function that returns the victim's username so the correct value is placed in the stats JSON data ------------------------------------ REvil 1.01 MD5: 2abff29b4d87f30f011874b6e98959e9 SHA1: 9d1b61b1cba411ee6d4664ba2561fa59cdb0732c SHA256: a88e2857a2f3922b44247316642f08ba8665185297e3cd958bbd22a83f380feb * Removes the exp/privilege escalation requirement for full execution and encrypts data regardless of privilege level * Makes encryption of network mapped drives optional by adding the "-nolan" argument ------------------------------------ REvil 1.02 MD5: 4af953b20f3a1f165e7cf31d6156c035 SHA1: b859de5ffcb90e4ca8e304d81a4f81e8785bb299 SHA256: 89d80016ff4c6600e8dd8cfad1fa6912af4d21c5457b4e9866d1796939b48dc4 * Enhances whitelisting validation by adding inspection of GetUserDefaultUILanguage and GetSystemDefaultUILanguage * Partially implements "lock file" logic by generating a lock filename based on the first four bytes of the Base64-decoded pk key, appending a .lock file extension, and adding the filename to the list of whitelisted files in the REvil configuration (It does not appear that this value is referenced after it is created and stored in memory. There is no evidence that a lock file is dropped to disk.) * Enhances folder whitelisting logic that take special considerations if the folder is associated with "program files" directories * Hard-codes whitelisting of all direct content within the Program Files or Program Files x86 directories * Hard-codes whitelisting of "sql" subfolders within program files * Encrypts program files sub-folders that does not contain "sql" in the path * Compares other folders to the list of whitelisted folders specified in the REvil configuration to determine if they are whitelisted * Encodes stored strings used for URI building within the binary and decodes them in memory right before use * Introduces a REvil registry root key "sub_key" registry value containing the attacker's public key ------------------------------------ REvil 1.03 MD5: 3cae02306a95564b1fff4ea45a7dfc00 SHA1: 0ce2cae5287a64138d273007b34933362901783d SHA256: 78fa32f179224c46ae81252c841e75ee4e80b57e6b026d0a05bb07d34ec37bbf * Removes lock file logic that was partially implemented in 1.02 * Leverages WMI to continuously monitor for and kill newly launched processes whose names are listed in the prc configuration key (Previous versions performed this action once.) * Encodes stored shellcode * Adds the -path argument: * Does not wipe folders (even if wipe == true) * Does not set desktop background * Does not contact the C2 server (even if net == true) * Encrypts files in the specified folder and drops the ransom note * Changes the REvil registry root key to SOFTWARE\QtProject\OrganizationDefaults * Changes registry key values from --> to: * sub_key --> pvg * pk_key --> sxsP * sk_key --> BDDC8 * 0_key --> f7gVD7 * rnd_ext --> Xu7Nnkd * stat --> sMMnxpgk ------------------------------------ REvil 1.04 MD5: 6e3efb83299d800edf1624ecbc0665e7 SHA1: 0bd22f204c5373f1a22d9a02c59f69f354a2cc0d SHA256: 2ca64feaaf5ab6cf96677fbc2bc0e1995b3bc93472d7af884139aa757240e3f6 * Leverages PowerShell and WMI to delete shadow copies if the victim's operating system is newer than Windows XP (For Windows XP or older, it uses the original command that was executed in all previous REvil versions.) * Removes the folder wipe capability * Changes the REvil registry root key to SOFTWARE\GitForWindows * Changes registry key values from --> to: * pvg --> QPM * sxsP --> cMtS * BDDC8 --> WGg7j * f7gVD7 --> zbhs8h * Xu7Nnkd --> H85TP10 * sMMnxpgk --> GCZg2PXD ------------------------------------ REvil v1.05 MD5: cfefcc2edc5c54c74b76e7d1d29e69b2 SHA1: 7423c57db390def08154b77e2b5e043d92d320c7 SHA256: e430479d1ca03a1bc5414e28f6cdbb301939c4c95547492cdbe27b0a123344ea * Add new 'arn' configuration key that contains a boolean true/false value that controls whether or not to implement persistence. * Implements persistence functionality via registry Run key. Data for value is set to the full path and filename of the currently running executable. The executable is never moved into any 'working directory' such as %AppData% or %TEMP% as part of the persistence setup. The Reg Value used is the hardcoded value of 'lNOWZyAWVv' : * SOFTWARE\Microsoft\Windows\CurrentVersion\Run\lNOWZyAWVv * Before exiting, REvil sets up its malicious executable to be deleted upon reboot by issuing a call to MoveFileExW and setting the destination to NULL and the flags to 4 (MOVEFILE_DELAY_UNTIL_REBOOT). This breaks persistence however as the target executable specified in the Run key will no longer exist once this is done. * Changes registry key values from --> to: * QPM --> tgE * cMtS --> 8K09 * WGg7j --> xMtNc * zbhs8h --> CTgE4a * H85TP10 --> oE5bZg0 * GCZg2PXD --> DC408Qp4 ------------------------------------ REvil v1.06 MD5: 65ff37973426c09b9ff95f354e62959e SHA1: b53bc09cfbd292af7b3609734a99d101bd24d77e SHA256: 0e37d9d0a7441a98119eb1361a0605042c4db0e8369b54ba26e6ba08d9b62f1e * Updated string decoding function to break existing yara rules. Likely the result of the blog posted by us. * Modified handling of network file encryption. Now explicitly passes every possible "Scope" constant to the WNetOpenEnum function when looking for files to encrypt. It also changed the 'Resource Type" from RESOURCETYPE_DISK to RESOURCETYPE_ANY which will now include things like mapped printers. * Persistence registry value changed from 'lNOWZyAWVv' to 'sNpEShi30R' * Changes registry key values from --> to: * tgE --> 73g * 8K09 --> vTGj * xMtNc --> Q7PZe * CTgE4a --> BuCrIp * oE5bZg0 --> lcZd7OY * DC408Qp4 --> sLF86MWC ------------------------------------ REvil v1.07 MD5: ea4cae3d6d8150215a4d90593a4c30f2 SHA1: 8dcbcbefaedf5675b170af3fd44db93ad864894e SHA256: 6a2bd52a5d68a7250d1de481dcce91a32f54824c1c540f0a040d05f757220cd3 TBD

aka DELIMEAT

Symantec describes this as a malware written as Windows kernel driver, used by China-linked threat actors. The malware has a custom TCP/IP stack and is capable of hijacking connections.

According to Koi Security, this malware harvests NPM, GitHub, and Git credentials for supply chain propagation. It targets 49 different cryptocurrency wallet extensions to drain funds. It uses stolen credentials to compromise additional packages and extensions, spreading the worm further. Furthermore, it deploys SOCKS proxy servers, turning developer machines into criminal infrastructure and installs hidden VNC servers for complete remote access.

Browser information stealer, written in Go.

Honeypot-aware variant of Mirai.

aka Gafgyt, gayfgt, lizkebab +2

Bashlite is a malware family which infects Linux systems in order to launch distributed denial-of-service attacks (DDoS). Originally it was also known under the name Bashdoor, but this term now refers to the exploit method used by the malware. It has been used to launch attacks of up to 400 Gbps.

aka PlayCrypt

According to PCrisk, PLAY is the name of a ransomware-type program. Malware categorized as such operates by encrypting data and demanding ransoms for the decryption. After we executed a sample of this ransomware on our test machine, it encrypted files and appended their filenames with a ".PLAY" extension. For example, a file titled "1.jpg" appeared as "1.jpg.PLAY", "2.png" as "2.png.PLAY", etc. Once the encryption process was completed, PLAY created a text file named "ReadMe.txt" on the desktop.

Icarus is a modular stealer software, written in .NET. One module is the open source r77 rootkit.

According to the author, Evilginx is a standalone man-in-the-middle attack framework used for phishing login credentials along with session cookies, allowing for the bypass of 2-factor authentication.

aka Destroy RAT, Kaba, Korplug +3

RSA describes PlugX as a RAT (Remote Access Trojan) malware family that is around since 2008 and is used as a backdoor to control the victim's machine fully. Once the device is infected, an attacker can remotely execute several kinds of commands on the affected system. Notable features of this malware family are the ability to execute commands on the affected machine to retrieve: machine information capture the screen send keyboard and mouse events keylogging reboot the system manage processes (create, kill and enumerate) manage services (create, start, stop, etc.); and manage Windows registry entries, open a shell, etc. The malware also logs its events in a text log file.

aka POISONPLUG.SHADOW, XShellGhost

Ryuk is a ransomware which encrypts its victim's files and asks for a ransom via bitcoin to release the original files. It is has been observed being used to attack companies or professional environments. Cybersecurity experts figured out that Ryuk and Hermes ransomware shares pieces of codes. Hermes is commodity ransomware that has been observed for sale on dark-net forums and used by multiple threat actors.

According to sysdig, SNOWLIGHT is used as a dropper for its fileless payload (vshell).

aka Farfli, Gh0st RAT, PCRat

According to Security Ninja, Gh0st RAT (Remote Access Terminal) is a trojan “Remote Access Tool” used on Windows platforms, and has been used to hack into some of the most sensitive computer networks on Earth. Below is a list of Gh0st RAT capabilities. Take full control of the remote screen on the infected bot. Provide real time as well as offline keystroke logging. Provide live feed of webcam, microphone of infected host. Download remote binaries on the infected remote host. Take control of remote shutdown and reboot of host. Disable infected computer remote pointer and keyboard input. Enter into shell of remote infected host with full control. Provide a list of all the active processes. Clear all existing SSDT of all existing hooks.

aka ALPHV, Noberus

ALPHV, also known as BlackCat or Noberus, is a ransomware family that is deployed as part of Ransomware as a Service (RaaS) operations. ALPHV is written in the Rust programming language and supports execution on Windows, Linux-based operating systems (Debian, Ubuntu, ReadyNAS, Synology), and VMWare ESXi. ALPHV is marketed as ALPHV on cybercrime forums, but is commonly called BlackCat by security researchers due to an icon of a black cat appearing on its leak site. ALPHV has been observed being deployed in ransomware attacks since November 18, 2021. ALPHV can be configured to encrypt files using either the AES or ChaCha20 algorithms. In order to maximize the amount of ransomed data, ALPHV can delete volume shadow copies, stop processes and services, and stop virtual machines on ESXi servers. ALPHV can self-propagate by using PsExec to remote execute itself on other hosts on the local network.

AsyncRAT is a Remote Access Tool (RAT) designed to remotely monitor and control other computers through a secure encrypted connection. It is an open source remote administration tool, however, it could also be used maliciously because it provides functionality such as keylogger, remote desktop control, and many other functions that may cause harm to the victim’s computer. In addition, AsyncRAT can be delivered via various methods such as spear-phishing, malvertising, exploit kit and other techniques.

VShell is an OST framework written in Go, enabling availability of implants for multiple platforms (Windows, Linux, macOS).

aka LummaC2 Stealer

Lumma Stealer (aka LummaC2 Stealer) is an information stealer written in C language that has been available through a Malware-as-a-Service (MaaS) model on Russian-speaking forums since at least August 2022. It is believed to have been developed by the threat actor "Shamel", who goes by the alias "Lumma". Lumma Stealer primarily targets cryptocurrency wallets and two-factor authentication (2FA) browser extensions, before ultimately stealing sensitive information from the victim's machine. Once the targeted data is obtained, it is exfiltrated to a C2 server via HTTP POST requests using the user agent "TeslaBrowser/5.5"." The stealer also features a non-resident loader that is capable of delivering additional payloads via EXE, DLL, and PowerShell.

According to PCrisk, XMRIG is a completely legitimate open-source application that utilizes system CPUs to mine Monero cryptocurrency. Unfortunately, criminals generate revenue by infiltrating this app into systems without users' consent. This deceptive marketing method is called "bundling". In most cases, "bundling" is used to infiltrate several potentially unwanted programs (PUAs) at once. So, there is a high probability that XMRIG Virus came with a number of adware-type applications that deliver intrusive ads and gather sensitive information.

Cisco Talos reports that this is a data exfiltration tool used by TA505.