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MalwareUsed by 4 actors

RainyDay

RainyDay is a backdoor associated with the Firefly group, also known as Naikon. Reported capabilities include collecting credentials from web browsers, capturing screenshots, using TCP for command-and-control communications, and leveraging proxy tooling such as boost_proxy_client for reverse proxy functionality. It can establish persistence via scheduled tasks and can also create and register a Windows service for execution. Execution has also been observed via side-loading of malicious executables. For data theft, RainyDay can stage files in C:\ProgramData\Adobe\temp prior to exfiltration and can use a file exfiltration tool to upload specific files to Dropbox. It has used filenames intended to mimic legitimate software, including vmtoolsd.exe to spoof VMware Tools. The content also notes that a newer variant has features overlapping both the RainyDay and Turian backdoors.

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THREAT ACTORS

Groups observed using it

4 distinct threat actors attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.

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Lotus Blossom

The new variant's features overlap with both the RainyDay and Turian backdoors...

via the hacker newsthehackernews.com
naikon_apt

The new variant's features overlap with both the RainyDay and Turian backdoors...

via the hacker newsthehackernews.com
Naikon

Rainyday: A backdoor associated with the Firefly group (aka Naikon).

via symantec blogsecurity.com
Firefly

Rainyday: A backdoor associated with the Firefly group (aka Naikon).

via symantec blogsecurity.com
MITRE ATT&CK

Techniques & procedures

24 distinct techniques documented for this family, organized by ATT&CK tactic.

Execution

5 techniques
T1053Scheduled Task/JobEvidence1

“Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.” / “APT29 used scheduler and schtasks to create new tasks on remote host as part of their lateral movement… updating an existing legitimate task to execute their tools and then returned the scheduled task to its original configuration.”

T1053.005Scheduled TaskEvidence2

During the 2022 Ukraine Electric Power Attack, Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.

T1059.003Windows Command ShellEvidence3
TacticExecution

During the 2016 Ukraine Electric Power Attack, Sandworm Team used the xp_cmdshell command in MS-SQL. During the 2025 Poland Wiper Attacks, the adversaries leveraged PsExec to run cmd.exe commands on multiple victim machines. Numerous malware families and groups are described as using cmd.exe, cmd /c, Windows command shell, or command-line interfaces to execute commands, payloads, reconnaissance, persistence, cleanup, and ransomware actions.

T1106Native APIEvidence1
TacticExecution
T1574.001DLLEvidence1

"A version of the legitimate VLC Media Player masquerading as a Google file (googleupdate.exe) was used to sideload a Coolclient loader (file name: libvlc.dll)." / "The loader is sideloaded using a legitimate F-Secure executable named fsstm.exe." / "It is sideloaded using an executable called msproxy.exe..."

Persistence

3 techniques
T1053Scheduled Task/JobEvidence1

“Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.” / “APT29 used scheduler and schtasks to create new tasks on remote host as part of their lateral movement… updating an existing legitimate task to execute their tools and then returned the scheduled task to its original configuration.”

T1053.005Scheduled TaskEvidence2

During the 2022 Ukraine Electric Power Attack, Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.

T1543.003Windows ServiceEvidence1

“Sandworm Team used an arbitrary system service to load at system boot for persistence for Industroyer… replaced the ImagePath registry value of a Windows service with a new backdoor binary… [multiple groups/malware] creating a service / installing as a service / modifying service configurations for persistence.”

T1053Scheduled Task/JobEvidence1

“Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.” / “APT29 used scheduler and schtasks to create new tasks on remote host as part of their lateral movement… updating an existing legitimate task to execute their tools and then returned the scheduled task to its original configuration.”

T1053.005Scheduled TaskEvidence2

During the 2022 Ukraine Electric Power Attack, Sandworm Team leveraged Scheduled Tasks through a Group Policy Object (GPO) to execute CaddyWiper at a predetermined time.

T1543.003Windows ServiceEvidence1

“Sandworm Team used an arbitrary system service to load at system boot for persistence for Industroyer… replaced the ImagePath registry value of a Windows service with a new backdoor binary… [multiple groups/malware] creating a service / installing as a service / modifying service configurations for persistence.”

Stealth

7 techniques
T1027Obfuscated Files or InformationEvidence6
TacticStealth

The content repeatedly describes payloads, strings, configuration files, scripts, URLs, and binaries being obfuscated or encoded using Base64, XOR, RC4, AES, RSA, hex encoding, custom algorithms, and other methods across many malware families and threat actors.

T1027.013Encrypted/Encoded FileEvidence1
TacticStealth

Examples throughout the content include 'encrypted payloads decrypted and executed in memory,' 'encrypts its configuration file,' 'AES-encrypted resource,' 'RC4 encrypted embedded scripts,' and 'payload includes an encrypted main component.'

T1036MasqueradingEvidence2
TacticStealth

During the 2016 Ukraine Electric Power Attack, DLLs and EXEs with filenames associated with common electric power sector protocols were used to masquerade files.

T1036.005Match Legitimate Resource Name or LocationEvidence1
TacticStealth

Akira has used legitimate names and locations for files to evade defenses.

T1070.004File DeletionEvidence5
TacticStealth

The content repeatedly describes threat actors and malware deleting files, tools, scripts, logs, droppers, staged data, and artifacts from compromised systems to cover tracks, remove evidence, or self-delete.

T1140Deobfuscate/Decode Files or InformationEvidence3
TacticStealth

The content repeatedly describes malware and threat actors decoding, decrypting, or deobfuscating payloads, strings, configuration data, commands, and C2 traffic prior to execution or use, e.g., 'APT28 macro uses the command certutil -decode to decode contents of a .txt file storing the base64 encoded payload' and 'Action RAT can use Base64 to decode actor-controlled C2 server communications.'

T1574.001DLLEvidence1

"A version of the legitimate VLC Media Player masquerading as a Google file (googleupdate.exe) was used to sideload a Coolclient loader (file name: libvlc.dll)." / "The loader is sideloaded using a legitimate F-Secure executable named fsstm.exe." / "It is sideloaded using an executable called msproxy.exe..."

T1555.003Credentials from Web BrowsersEvidence4

The content repeatedly describes threat actors and malware stealing usernames, passwords, cookies, session tokens, and other saved credentials from web browsers such as Chrome, Firefox, Internet Explorer, Edge, Opera, Safari, and Yandex.

Discovery

3 techniques
T1007System Service DiscoveryEvidence1
TacticDiscovery

"actors used the following command ... to obtain information about services: net start"; "APT1 used the commands net start and tasklist to get a listing of the services on the system"; "OilRig has used sc query on a victim to gather information about services"; "Indrik Spider has used the win32_service WMI class to retrieve a list of services"

T1057Process DiscoveryEvidence2
TacticDiscovery

The content repeatedly describes malware and threat actors obtaining lists of running processes, using utilities such as tasklist, ps, WMI, Get-Process, CreateToolhelp32Snapshot, EnumProcesses, and similar APIs/commands to enumerate active processes on victim systems.

T1083File and Directory DiscoveryEvidence4
TacticDiscovery

BADNEWS crawls the victim's local drives and collects documents with selected extensions; Machete searches the file system for files of interest; Rover searches for files on local drives based on a predefined list of file extensions.

Collection

3 techniques
T1005Data from Local SystemEvidence2

The content repeatedly describes threat actors and malware collecting, stealing, identifying, copying, or staging files, documents, credentials, logs, databases, and other information from compromised hosts or local systems.

T1074Data StagedEvidence1

The content repeatedly describes adversaries and malware storing collected data, command output, credentials, archives, or files in local temporary folders, working directories, hidden directories, registry locations, recycle bins, or specific files prior to exfiltration.

T1113Screen CaptureEvidence1

"Agent Tesla can capture screenshots of the victim’s desktop"; "AppleSeed can take screenshots on a compromised host"; "APT28 has used tools to take screenshots from victims"; "Cobalt Strike's Beacon payload is capable of capturing screenshots"; "PowerSploit's Get-TimedScreenshot Exfiltration module can take screenshots at regular intervals"; "Hydraq includes a component based on the code of VNC that can stream a live feed of the desktop"

T1071.001Web ProtocolsEvidence2

The content repeatedly describes threat actors, malware, and campaigns using HTTP and/or HTTPS for command and control, including examples such as BlackEnergy communicating with C2 over HTTP POST requests and many other families using HTTP/S for C2.

T1090ProxyEvidence1
T1090.001Internal ProxyEvidence2

"APT41 used a tool called CLASSFON to covertly proxy network communications." / "BADCALL functions as a proxy server between the victim and C2 server." / "Sandworm Team's BCS-server tool can create an internal proxy server to redirect traffic..."

T1105Ingress Tool TransferEvidence1

Exfiltration

1 technique
T1567.002Exfiltration to Cloud StorageEvidence2

Akira will exfiltrate victim data using applications such as Rclone. APT41 DUST exfiltrated collected information to OneDrive. BoomBox can upload data to dedicated per-victim folders in Dropbox. During C0015, the threat actors exfiltrated files and sensitive data to the MEGA cloud storage site using the Rclone command.

What this page doesn’t show

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IOC matching

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Threat actor attribution4

Named campaigns wielding this family, with evidence pinned to each claim.

Exploited vulnerabilities

CVEs this family uses for access and lateral movement.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

MITRE ATT&CK mapping24

Every documented technique, ranked by evidence weight.

Researcher chatter

Reddit, Mastodon, and CTI community discussion around this family.