Clop
Cl0p is a ransomware and extortion malware family/group active since 2019, widely assessed as a successor to CryptoMix and commonly tracked with aliases including Cl0p and Clop. Reporting in the provided content also links the operation to TA505, FIN11, Lace Tempest, DEV-0950, and UNC2546 in various contexts. Cl0p has targeted organizations worldwide across retail, transportation, education, manufacturing, automotive, energy, financial, telecommunications, healthcare, government, and other sectors.
The malware and associated operation are known for both traditional ransomware behavior and large-scale extortion-only campaigns centered on data theft. The content states that Cl0p often steals data before encryption and publicly names non-paying victims on its leak site. In multiple major campaigns, including GoAnywhere and MOVEit, Cl0p emphasized pure extortion through exfiltration rather than encryption. Cisco Talos specifically noted that Clop primarily focused on extortion through data theft rather than encryption and is one of the few ransomware actors highlighted for exploiting zero-day vulnerabilities.
Initial access and propagation in the provided reporting include exploitation of managed file transfer and similar enterprise software. Cl0p is described as exploiting Accellion FTA vulnerabilities in 2020, SolarWinds Serv-U CVE-2021-35211 in 2021, GoAnywhere MFT CVE-2023-0669 in 2023, MOVEit Transfer CVE-2023-34362 and related MOVEit flaws in 2023, Cleo Harmony/VLTrader/LexiCom CVE-2024-50623 and CVE-2024-55956 in 2024, and Oracle E-Business Suite BI Publisher Integration CVE-2025-61882 in 2025. The MOVEit campaign is described as a mass exploitation operation that stole data from hundreds to thousands of organizations, while the Cleo campaign involved deployment of malicious Freemarker template backdoor code and the Java backdoor Malichus for command execution, further access, and data theft. In Serv-U intrusions, reporting cited PowerShell-based deployment of Cobalt Strike, reconnaissance, lateral movement, and persistence via hijacking the RegIdleBackup scheduled task to load FlawedGrace RAT.
Behavior and capabilities directly attributed to Cl0p in the content include disabling or uninstalling security products; checking keyboard layout and text charset via GetKeyboardLayout() and GetTextCharset to avoid installation on Russian-language or other CIS-language systems; deleting shadow copies with "vssadmin Delete Shadows /all /quiet"; and using bcdedit to disable recovery options. The content also notes use of net.exe, taskkill.exe, and vssadmin.exe during encryption to stop services, kill processes, and impair recovery. Mandiant analyzed a CLOP-family sample with a hardcoded process termination list that included OT-related strings and attributed associated deployment to FIN11, indicating potential risk to operational technology environments even though no specialized OT expertise was established.
The provided content also describes the first observed Linux ELF variant of Cl0p. That variant was identified in late December 2022 and likely used in an attack against a university in Colombia. It targeted files in /opt, /u01, /u02, /u03, /u04, /home, and /root, created a child process with fork, called umask(0), setsid, and chdir("/"), and dropped the ransom note README_C_I_0P.TXT. It used per-file RC4 keys but protected them incorrectly with a hardcoded RC4 master key ("Jfkdskfku2ir32y7432uroduw8y7318i9018urewfdsZ2Oaifwuieh~~cudsffdsd") instead of RSA, allowing decryption without paying the ransom. The Linux variant used the .C_I_0P extension, shared contact emails unlock@support-mult.com and unlock@rsv-box.com with Windows variants, and had a reported SHA1 of 46b02cc186b85e11c3d59790c3a0bfd2ae1f82a5.
Notable indicators and artifacts mentioned in the content include the Linux ransom note name README_C_I_0P.TXT, Windows ransom note !_READ_ME.RTF, the .C_I_0P extension, the Linux sample SHA1 46b02cc186b85e11c3d59790c3a0bfd2ae1f82a5, and a CLOP-family sample MD5 3b980d2af222ec909b948b6bbdd46319. For Serv-U exploitation, the content highlights the log string "EXCEPTION: C0000005; CSUSSHSocket::ProcessReceive();" and suspicious PowerShell execution as signs of compromise. For MOVEit exploitation, the content states that Cl0p deployed specially crafted webshells to enumerate and download files and steal Azure Blob Storage credentials or secrets.
Overall, the content portrays Cl0p as a prolific ransomware/extortion threat that combines data theft, public leak-site pressure, defense evasion, recovery inhibition, and repeated exploitation of high-impact zero-day vulnerabilities in enterprise file transfer and related platforms.
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Vulnerabilities exploited
22 CVEs Mallory has correlated with this family across public research and vendor advisories. Each row links to the full Mallory page for that vulnerability.
TA505 (Clop) is one of the oldest groups, active since 2019... It has been exploiting the Cleo zero-day vulnerability (CVE-2024–55956) since late 2024, which makes it the most active of all groups in the first half of 2025.
ICYMI: Catch-up on events relating to the MOVEit data breach so far: ... MOVEit Data Breach [CVE-2023-34362]
Oracle published a security advisory about a vulnerability (CVE-2026-35273) in PeopleSoft, specifically in the Enterprise PeopleTools, versions 8.61 and 8.62. There is credible intelligence that this vulnerability is being actively exploited in the wild, however there is no publicly available proof-of-concept (PoC).
A remote code execution vulnerability (CVE-2021-35211) affecting SolarWinds Serv-U software has previously been exploited as a zero-day by suspected Chinese attackers for cyber espionage purposes, and later by the Cl0p ransomware outfit.
Cl0p (и связанный кластер FIN11) продолжила тактику массовой эксплуатации supply chain. По данным Cognyte, Cl0p провела кампанию с эксплуатацией критической zero-day CVE-2025-61882 ... в Oracle E-Business Suite (компонент BI Publisher Integration, версии 12.2.3-12.2.14). По данным NVD, CVSS 9.8 (Critical) ... эксплуатация не требует аутентификации и ведёт к полной компрометации. Уязвимость внесена в CISA KEV 2025-10-06. Около 30 организаций были опубликованы на DLS Cl0p с эксфильтрацией сотен гигабайт из Oracle EBS. | По данным Cognyte, Cl0p провела кампанию с эксплуатацией критической zero-day CVE-2025-61882 ... в Oracle E-Business Suite ... Около 30 организаций были опубликованы на DLS Cl0p с эксфильтрацией сотен гигабайт из Oracle EBS.
PaperCut servers have been previously breached by ransomware gangs in 2023 by exploiting a critical, unauthenticated remote code execution (RCE) vulnerability (CVE–2023–27350)... One month later, CISA and the FBI issued a joint advisory warning that the Bl00dy Ransomware gang had also begun exploiting the CVE-2023–27350 RCE vulnerability to gain initial access to the networks of educational organizations.
PaperCut servers have been previously breached by ransomware gangs in 2023 by exploiting a critical, unauthenticated remote code execution (RCE) vulnerability (CVE–2023–27350) and a high-severity information disclosure flaw (CVE–2023–27351).
On 11 October 2025, Oracle released an emergency fix for a high-severity information disclosure vulnerability in Oracle E-Business Suite (EBS), tracked as CVE-2025-61884. The flaw exists in the Runtime UI component of Oracle Configurator and allows remote unauthenticated threat actors to access sensitive resources.
Cl0p Ransomware, aka Cl0p, is a ransomware group that emerged in February 2019 and targeted most industries worldwide, including retail, transportation, education, manufacturing, automotive, energy, financial, telecommunications and even healthcare. | Cl0p exploited a zero-day vulnerability in Cleo LexiCom, Cleo VLTrader, and Cleo Harmony products to steal data. The vulnerability, tracked as CVE-2024-50623, enables remote file uploads and downloads, leading to remote code execution. A fix has been released for affected Cleo products (version 5.8.0.21), but researchers have warned that the patch may be bypassed. Huntress disclosed the active exploitation of the vulnerability and provided a proof-of-concept to demonstrate its potential impact.
CL0P have utilized this tactic in the targeting of organizations using a vulnerable version of ‘Accellion FTA’, a file transfer appliance. As such, following vulnerabilities have reportedly been exploited to gain access to victim data as well as potentially pivoting into victim networks: CVE-2021-27101 – Critical SQL Injection via a crafted Host header in versions ≤9_12_370. | Cl0p Ransomware, aka Cl0p, is a ransomware group that emerged in February 2019 and targeted most industries worldwide, including retail, transportation, education, manufacturing, automotive, energy, financial, telecommunications and even healthcare.
CL0P have utilized this tactic in the targeting of organizations using a vulnerable version of ‘Accellion FTA’, a file transfer appliance. As such, following vulnerabilities have reportedly been exploited to gain access to victim data as well as potentially pivoting into victim networks: CVE-2021-27104 – Critical command execution via a crafted POST in versions ≤9_12_370. | Cl0p Ransomware, aka Cl0p, is a ransomware group that emerged in February 2019 and targeted most industries worldwide, including retail, transportation, education, manufacturing, automotive, energy, financial, telecommunications and even healthcare.
CL0P have utilized this tactic in the targeting of organizations using a vulnerable version of ‘Accellion FTA’, a file transfer appliance. As such, following vulnerabilities have reportedly been exploited to gain access to victim data as well as potentially pivoting into victim networks: CVE-2021-27102 – Command execution via a local web service call in versions ≤9_12_411. | Cl0p Ransomware, aka Cl0p, is a ransomware group that emerged in February 2019 and targeted most industries worldwide, including retail, transportation, education, manufacturing, automotive, energy, financial, telecommunications and even healthcare.
CL0P have utilized this tactic in the targeting of organizations using a vulnerable version of ‘Accellion FTA’, a file transfer appliance. As such, following vulnerabilities have reportedly been exploited to gain access to victim data as well as potentially pivoting into victim networks: CVE-2021-27103 – Critical server-side request forgery (SSRF) in versions ≤9_12_411. | Cl0p Ransomware, aka Cl0p, is a ransomware group that emerged in February 2019 and targeted most industries worldwide, including retail, transportation, education, manufacturing, automotive, energy, financial, telecommunications and even healthcare.
Cl0p is a type of ransomware that has been used in cyberattacks since 2019.
Cl0p is a type of ransomware that has been used in cyberattacks since 2019.
Further, two of their domain controllers were left completely unpatched against ZeroLogon (CVE-2020-1472), a critical, easily exploitable vulnerability published years before the intrusion.
These threat actors have expanded their attacks by exploiting two additional vulnerabilities (CVE-2025-11371 and CVE-2025-30406) to bypass authentication controls, execute malicious code, and steal data on the target server. CVE-2025-30406 ... A vulnerability caused due to CentreStack portal’s hardcoded machinekey use. Enables threat actors to serialize a payload server-side deserialization to achieve RCE.
These threat actors have expanded their attacks by exploiting two additional vulnerabilities (CVE-2025-11371 and CVE-2025-30406) to bypass authentication controls, execute malicious code, and steal data on the target server. In the default installation and configuration of Gladinet CentreStack and TrioFox, there is an unauthenticated Local File Inclusion Flaw that allows unintended disclosure of system files. Exploitation of this vulnerability has been observed in the wild.
CISA added CVE-2025-14611 to its Known Exploited Vulnerabilities (KEV) Catalog on Dec. 15, 2025. This critical insecure cryptography vulnerability affects Gladinet CentreStack and TrioFox products prior to version 16.12.10420.56791. Threat actors—including the known ransomware group Clop—are confirmed to have already exploited these vulnerabilities to gain access to organizations’ systems.
Prior to its patching, attackers linked to the Clop ransomware operation were already exploiting CVE-2023-34362 as a zero-day vulnerability. | Earlier this year it was responsible for exploiting a zero-day vulnerability (CVE-2023-0669) in the GoAnywhere MFT platform.
The campaign exploits multiple remotely accessible vulnerabilities patched by Oracle in its July 2025 Critical Patch Update (notably CVE-2025-30745, CVE-2025-30746, and CVE-2025-50107).
The campaign exploits multiple remotely accessible vulnerabilities patched by Oracle in its July 2025 Critical Patch Update (notably CVE-2025-30745, CVE-2025-30746, and CVE-2025-50107).
Groups observed using it
8 distinct threat actors attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
По данным Cognyte, Cl0p провела кампанию с эксплуатацией критической zero-day CVE-2025-61882 ... в Oracle E-Business Suite ... Около 30 организаций были опубликованы на DLS Cl0p с эксфильтрацией сотен гигабайт из Oracle EBS.
The most notorious among these are campaigns involving banking Trojans such as Dridex and TrickBot, ransomware such as Clop/Cryptomix and MINEBRIDGE...
Cl0p Ransomware, aka Cl0p, is a ransomware group that emerged in February 2019 and targeted most industries worldwide, including retail, transportation, education, manufacturing, automotive, energy, financial, telecommunications and even healthcare.
Microsoft has linked the Clop ransomware gang to recent attacks exploiting a zero-day vulnerability in the MOVEit Transfer platform to steal data from organizations.
Prior to its patching, attackers linked to the Clop ransomware operation were already exploiting CVE-2023-34362 as a zero-day vulnerability.
DefenderDetection ... default: Win32/Clop|Win32/TurtleLoader
Techniques & procedures
24 distinct techniques documented for this family, organized by ATT&CK tactic.
Initial Access
5 techniques
Initial Access
victims failing to meet their ransom demands are promptly ‘named and shamed’ on ‘CL0P^_- LEAKS’, the group’s Tor-hosted leak site... CL0P provide multiple contact email addresses as well as, more recently, a link to an online chat feature on their Tor hidden service
On May 31st, Progress Software issued an advisory and patch for a vulnerability subsequently identified as CVE-2023-34362 ... The company stated the vulnerability “could lead to escalated privileges and potential unauthorized access to the environment.” ... it later emerged had been happening since at least May 27th.
Whist CL0P are thought to make use of broad malicious email (malspam) campaigns to identify potential corporate victims... In the case of malspam campaigns, the group are thought to send their initial lures during the working week.
CL0P malspam campaigns have been observed as using data stolen from existing victims. As such, customers, partners or vendors of any victim organization could potentially be targeted with incredibly convincing email lures, especially if the group were to infiltrate and send malicious email lures from the original victim’s email server.
Execution
1 technique
Execution
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.
Persistence
3 techniques
Persistence
The content repeatedly describes threat actors and malware modifying, creating, deleting, or storing data in Windows Registry keys and values for persistence, configuration storage, defense evasion, credential access, privilege escalation, and execution.
victims failing to meet their ransom demands are promptly ‘named and shamed’ on ‘CL0P^_- LEAKS’, the group’s Tor-hosted leak site... CL0P provide multiple contact email addresses as well as, more recently, a link to an online chat feature on their Tor hidden service
Privilege Escalation
1 technique
Privilege Escalation
Stealth
4 techniques
Stealth
Then by using the RC4 “master-key” the ransomware encrypts the generated RC4 key and stores it to $filename.$clop_extension.
Defense Impairment
2 techniques
Defense Impairment
The content repeatedly describes threat actors and malware modifying, creating, deleting, or storing data in Windows Registry keys and values for persistence, configuration storage, defense evasion, credential access, privilege escalation, and execution.
The content repeatedly describes threat actors and malware using valid, stolen, forged, self-signed, or abused code-signing certificates to sign malware and appear legitimate, including examples such as AppleJeus using a valid digital signature from Sectigo, APT41 leveraging code-signing certificates, FIN7 signing Carbanak payloads, and SUNBURST being digitally signed by SolarWinds.
Discovery
4 techniques
Discovery
Initially, the ransomware creates a new process by calling fork and exits the parent-process. The child-process sets its file mode creation mask... It then calls setsid, creates a session and sets the process group ID.
The content repeatedly describes malware and threat actors listing files and directories, enumerating drives, searching for files by extension/name/path, retrieving file metadata, and browsing file systems (for example: "APT28 has used Forfiles to locate PDF, Excel, and Word documents during collection" and "cmd can be used to find files and directories with native functionality such as dir commands").
It tries to access root by changing the working directory to “/” (chdir(“/”)). Once the permissions are set, the ransomware proceeds encrypting other directories.
Avaddon checks for specific keyboard layouts and OS languages to avoid targeting Commonwealth of Independent States (CIS) entities... Bazar can perform a check to ensure that the operating system's keyboard and language settings are not set to Russian... Clop has checked the keyboard language using the GetKeyboardLayout() function... Ryuk has been observed to query the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\Language and the value InstallLanguage.
Collection
3 techniques
Collection
the exfiltration of sensitive and valuable data prior to encryption... In addition to the wholesale theft of data from file servers and network storage devices... CL0P have repeatedly demonstrated their ability to gather large data stores including those used by database and email servers.
Exfiltration
2 techniques
Exfiltration
Impact
5 techniques
Impact
encrypt the data using the Windows CryptoAPI and then writing this encrypted data to a new file before the original is deleted.
Numerous ransomware/wiper examples enumerate files before encryption, such as "BlackCat can enumerate files for encryption", "NotPetya searches for files ending with dozens of different file extensions prior to encryption", and "WastedLocker can enumerate files and directories just prior to encryption."
The earliest iteration we identified of the shared kill list was a batch script deployed alongside LockerGoga... Other iterations of the list we have observed are also hardcoded directly into the ransomware binaries.
Akira will delete system volume shadow copies via PowerShell commands. Avaddon deletes backups and shadow copies using native system tools. Babuk has the ability to delete shadow volumes using vssadmin.exe delete shadows /all /quiet. BlackCat can delete shadow copies using vssadmin.exe delete shadows /all /quiet and wmic.exe Shadowcopy Delete; it can also modify the boot loader using bcdedit /set {default} recoveryenabled No.
IOCs tracked for this family
193 indicators attributed across vendor reports, sandbox runs, and researcher write-ups. Full values are available in Mallory.
IPs, domains, and DNS infrastructure linked to this family.
File hashes (MD5, SHA-1, SHA-256) from samples and reports.
Other indicator types observed in public reporting.
Recent activity
200 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A ransomware family referenced for its mass exploitation activity that inflated Q1 2025 victim counts.
Ransomware family associated here with mass exploitation of Oracle E-Business Suite via CVE-2025-61882 and subsequent large-scale data exfiltration and publication on its leak site.
Ransomware family used by the Cl0p group; in this incident it was tied to a long-term intrusion culminating in large-scale data exfiltration and publication of stolen data on Cl0p’s Tor leak site.
A ransomware operation noted here for mass-exploitation campaigns whose victim distribution mirrors the installed base of exploited enterprise software, including Cleo and Oracle EBS-related campaigns.
The version that knows your environment.
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.