FELIXROOT, also referred to as GreyEnergy mini, is a lightweight first-stage Windows backdoor associated in the provided content with malicious document delivery. The content states that it does not require administrative privileges. Observed behavior includes collecting the victim username and time zone, checking for installed security software such as antivirus and firewall products, and querying the Windows Registry for proxy information and potential privilege-escalation opportunities. It uses WMI to query the Windows Registry and has been observed using rundll32 to execute the dropper program. The malware encrypts collected data with AES and Base64 before sending it to its command-and-control server. Cleanup behavior described in the content includes deleting the Registry key HKCU\Software\Classes\Applications\rundll32.exe\shell\open, deleting a .LNK file from the startup directory, and removing dropper components. The content also notes that FELIXROOT can execute batch scripts and launch a reverse shell for command execution.
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1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
We have observed that malicious documents have been dropping “GreyEnergy mini”, a lightweight first-stage backdoor that does not require administrative privileges... GreyEnergy mini is also known as FELIXROOT.
20 distinct techniques documented for this family, organized by ATT&CK tactic.
FELIXROOT queries the Registry for specific keys for potential privilege escalation and proxy information. FELIXROOT has also used WMI to query the Windows Registry.
When a Web server is hosted internally and connected to the rest of an organization's network, the attackers have typically used that to try and move laterally on the network and plant backup backdoors so they can reinfect a victim network if their malware is spotted and removed.
Many entries explicitly state malware 'can create a reverse shell' or 'launch a remote shell,' including 4H RAT, AuditCred, BLACKCOFFEE, Carbanak, DarkComet, Exaramel for Windows, PlugX, QuasarRAT, and ZxShell. | The content repeatedly describes use of cmd.exe, cmd /c, Windows command shell, and xp_cmdshell to execute commands, run payloads, launch binaries, perform reconnaissance, persistence, cleanup, and ransomware actions. Examples include: 'Sandworm Team used the xp_cmdshell command in MS-SQL', 'APT41 used cmd.exe /c to execute commands on remote machines', and many malware families 'can use cmd.exe to execute commands on a compromised host.' | The content repeatedly mentions '.bat', '.cmd', and 'batch scripts' used to automate execution, persistence, cleanup, deployment, disabling security tools, and ransomware operations. Examples: 'APT1 has used ... batch scripting to automate execution', 'Blue Mockingbird has used batch script files to automate execution and deployment of payloads', and 'Cinnamon Tempest has executed ransomware using batch scripts deployed via GPO.'
During the 2015 Ukraine Electric Power Attack, Sandworm Team modified in-registry Internet settings to lower internet security before launching rundll32.exe ... AADInternals can modify registry keys ... ADVSTORESHELL is capable of setting and deleting Registry values ... [many additional examples].
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.
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.'
Bisonal has deleted Registry keys to clean up its prior activity ... FIN8 has deleted Registry keys during post compromise cleanup activities ... SUNBURST ... deleted previously-created Image File Execution Options (IFEO) Debugger registry values and registry keys related to HTTP proxy to clean up traces of its activity.
During the 2015 Ukraine Electric Power Attack, Sandworm Team modified in-registry Internet settings to lower internet security before launching rundll32.exe ... AADInternals can modify registry keys ... ADVSTORESHELL is capable of setting and deleting Registry values ... [many additional examples].
The content repeatedly describes malware and threat actors querying, enumerating, opening, and reading Windows Registry keys and values, e.g., "APT41 queried registry values to determine items such as configured RDP ports and network configurations" and "Reg may be used to gather details from the Windows Registry of a local or remote system at the command-line interface."
The content repeatedly describes malware and threat actors using commands and APIs such as ipconfig /all, ifconfig, arp -a, route print, nbtstat, netsh, GetAdaptersInfo, and GetIpNetTable to gather IP addresses, MAC addresses, DNS, DHCP, gateways, routing tables, ARP cache, proxy settings, domains, and network adapter/interface details.
The content repeatedly describes malware and threat actors collecting usernames, identifying logged-in users, running whoami/query user/quser, checking whether the current user is an administrator, enumerating user sessions, and gathering account details from compromised hosts.
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.
The content is a long ATT&CK-style listing of malware and threat actors that collect host details such as OS version, hostname, architecture, CPU, memory, BIOS, language, and other basic system characteristics; examples include use of commands like systeminfo, ver, uname, sw_vers, and WMI queries.
Multiple malware and threat groups are described as collecting/deriving local system time, date, timestamp, tick count, or time zone (e.g., "used time /t and net time \ip/hostname for system time discovery"; "collects the timestamp from the victim’s machine"; "can collect the time zone information from the system").
"AppleSeed has compressed collected data before exfiltration."; "APT28 used a publicly available tool to gather and compress multiple documents..."; "Aria-body has used ZIP to compress data..."; "Cadelspy...compress stolen data into a .cab file."; "Daserf hides collected data in password-protected .rar archives."; "FIN6 has compressed log files into a ZIP archive prior to staging and exfiltration."; "Lazarus Group has compressed exfiltrated data with RAR...archive specified directories in .zip format"; "XCSSET will compress entire ~/Desktop folders..."
35 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
FELIXROOT is a backdoor malware distributed via weaponized Microsoft Office documents exploiting CVE-2017-0199 and CVE-2017-11882. It provides remote access to compromised systems, allowing attackers to execute commands, upload/download files, and perform system reconnaissance. It uses custom encryption for its payloads and C2 communications, and attempts to evade detection by cleaning up after execution.
Rootkit/backdoor that uses WMI to query registry information.
Malware that queries registry keys for privilege escalation opportunities and proxy settings, including via WMI.
Malware that queries Registry keys for privilege-escalation opportunities and proxy settings.
Match every observed IP, domain, and hash against your live telemetry.
Named campaigns wielding this family, with evidence pinned to each claim.
CVEs this family uses for access and lateral movement.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Every documented technique, ranked by evidence weight.
Reddit, Mastodon, and CTI community discussion around this family.