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	"id": "a05d6a21-5b43-4cf5-8d03-5810456dbd36",
	"created_at": "2026-04-06T00:15:50.699978Z",
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	"title": "eSentire | Threat Intelligence Malware Analysis: DoubleZero",
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	"plain_text": "eSentire | Threat Intelligence Malware Analysis: DoubleZero\r\nBy eSentire Threat Response Unit (TRU)\r\nArchived: 2026-04-05 14:08:07 UTC\r\nDoubleZero is a newly emerging destructive malware targeting Ukrainian enterprises. The initial access vector is\r\nunknown, but eSentire Threat Intelligence assesses with medium confidence that the threat actor(s) was able to\r\ngain access to the infected machine(s) and escalate, or use, the existing administrative privileges to manually\r\nexecute the malware.\r\nAs the Russia-Ukraine crisis continues, we assess that destructive malware will continue to be actively deployed\r\nto disrupt the operations of Ukrainian infrastructure.\r\nKey Takeaways:\r\nDoubleZero is the fifth wiper malware targeting Ukrainian organizations (previously we have observed\r\nWhisperGate, HermeticWiper, IsaacWiper and CaddyWiper samples).\r\nThe malware destroys the components responsible for Windows boot process and overwrites the files will\r\nnull bytes.\r\nThe compilation timestamp was changed by the threat actor(s) to confuse the researchers and make it\r\nharder to evaluate how long ago the malware sample was written.\r\nTo achieve the full-scale disruption, the threat actor(s) would need to escalate their privileges or bypass the\r\nuser account control (UAC) to fully compromise the system.\r\neSentire Threat Intelligence team has observed that the malware fails to run on Windows Servers.\r\nCase Study\r\nOn March 22, 2022, the Computer Emergency Response Team of Ukraine (CERT-UA) released an advisory\r\nwarning about the destructive DoubleZero malware found on March 17, 2022. The malicious activity is tracked\r\nunder UAC-0088 and aimed to disrupt the operations of Ukrainian organizations.\r\nDoubleZero Analysis\r\nThe ZIP archives are named “Вирус... крайне опасно!!!.zip” which means “Virus…extremely dangerous!!!.zip”\r\nand csrss.zip. The archives contain two files:\r\ncpcrs.exe\r\ncsrss.exe\r\nThe 32-bit executables are compiled with .NET and both executables have the same impash, or import hash,\r\n2916dda3c80b39a540b60c072a91a915 (the hash that is calculated based on the library/APIs used and their order\r\nwithin the executable file). It means that both files have the same functionality.\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 1 of 11\n\nThe compilation timestamp dates to May 28, 2071, which is not valid.\r\nObfuscation\r\nThe .NET malware sample appears to be highly obfuscated (Exhibit 1).\r\nExhibit 1: Initial obfuscated .NET sample\r\nAfter the first round of de-obfuscation, we discovered that DoubleZero implements AES (block size 128-bit)\r\nencryption in EBC mode with PKCS padding, control flow and switch statements for additional code obfuscation\r\nas shown in Exhibit 2.\r\nExhibit 2: Obfuscation algorithm\r\nEnumeration\r\nThe sample enumerates the HKEY_CURRENT_USER, HKEY_USERS, HKEY_LOCAL_MACHINE registry keys\r\nincluding HKEY_LOCAL_MACHINE\\BCD00000000 (the key contains the boot configuration data that is required\r\nto boot up the Windows system) and subkeys using GetSubKeyNames, Registry.LocalMachine and\r\nRegistry.CurrentUser properties to remove them later.\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 2 of 11\n\nThe malware also enumerates on the paths listed in Exhibit 3 using Regex to match as few characters as possible\r\nwith (.*?), also known as lazy mode, and “.*” to match any character except for line terminators.\r\nThe paths queried:\r\n\\\\Users\\\\\\\\.*?\\\\\\\\Local Settings.*\r\n\\\\Users\\\\\\\\.*?\\\\\\\\AppData\\\\\\\\Local\\\\\\\\Application Data.*\r\n\\\\Users\\\\\\\\.*?\\\\\\\\Start Menu.*\r\n\\\\Users\\\\\\\\.*?\\\\\\\\Application Data.*\r\n\\\\ProgramData\\\\\\\\Microsoft.*\r\n\\\\Users\\\\\\\\.*?\\\\\\\\AppData\\\\\\\\Local\\\\\\\\Microsoft.*\r\n\\\\Users\\\\\\\\.*?\\\\\\\\AppData\\\\\\\\Roaming\\\\\\\\Microsoft.*\r\nExhibit 3: Enumerating the folders using regex\r\nThe following folders get concatenated together forming a path (Exhibit 4):\r\nProgramFiles(x86)\\Documents and Settings\r\nProgramFiles(x86)\\ProgramData\\Application Data\r\nProgramFiles(x86)\\Users\\All Users\r\nProgramFiles(x86)\\Users\\Default User\r\nExhibit 4: Folder concatenation\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 3 of 11\n\nIt is notable that the sample also enumerates through drivers (Exhibit 4) and C:\\Windows\\NTDS path. The NTDS\r\nfile contains a database that stores Active Directory data, including information groups, group membership and\r\nuser objects. It also includes the password hashes for all users in the domain. eSentire Threat Intelligence team\r\nobserved that the malware does not run on the Windows Server.\r\nThe malware gets the root drive of the infected device and Operating System information using\r\nEnvironment.SystemDirectory and Environment.OSVersion properties (Exhibit 5).\r\nExhibit 5: Enumerating system directory and OS version\r\nDoubleZero attempts to get all logical drives on the infected computers (Exhibits 6-7).\r\nExhibit 6: GetLogicalDrives gets a bitmask representing the currently available disk drives\r\nExhibit 7: Checks if the drive name is valid\r\nThree DLLs (Dynamic Link Library) will be used in this sample (Exhibit 8):\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 4 of 11\n\nntdll.dll\r\nkernel32.dll\r\nuser32.dll\r\nExhibit 8: DLLs used in DoubleZero\r\nIn Exhibit 9, the variables highlighted in orange are some of the API calls available for use by DoubleZero:\r\nNtOpenFile: this function opens an existing file, directory, device or volume then returns a handle for the\r\nfile object.\r\nNtFsControlFile: sends a control code to the specified file system or driver to perform specific action.\r\nRtlNtStatusToDosError: returns the system error code.\r\nRtlAdjustPrivilege: disables or enables a privilege from the calling thread or process.\r\nCloseHandle: closes handles to objects mention in Microsoft MSDN.\r\nGetFileSizeEx: gets the size of a file.\r\nGetLastError: receives the calling thread's last-error code value.\r\nExitWindowsEx: logs interactive user off, shuts down the system, or shuts down and restarts the system.\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 5 of 11\n\nExhibit 9: API calls via the appropriate DLLs\r\nIn addition to the API calls, the malware attempts to set the appropriate access control or full access rights to the\r\nfollowing files to fill them with zeroes (Exhibit 10):\r\nBOOTMGR (boot manager) including BCD (Boot Configuration Data) file, which are responsible for\r\nWindows startup process.\r\nBOOTSECT.BAK, which is a backup of the BOOTSECT.DOS. that is created by default by old Windows\r\noperating systems when any boot modifications take place.\r\npagefile.sys, which supports system crash dumps and used to manage virtual memory.\r\nswapfile.sys, which is used in conjunction with pagefile.sys to free up the memory in RAM.\r\nExhibit 10: Modifying access control rights\r\nData Destruction\r\nThe NtFsControlFile is responsible for zeroing the data out with the IOCTL code FSCTL_SET_ZERO_DATA\r\n(0x980c8) if it was able to open the file with NtOpenFile API (Exhibit 11). The number of bytes to be zeroed out\r\nare equal to the size of the file.\r\nExhibit 11: API responsible for wiping the data\r\nAfter the sample finishes executing, the system will automatically restart, and the user will get a prompt that the\r\nBCD file is missing or corrupted (Exhibit 12). The executables need to be run as an Administrator for it to gain the\r\nfull access to the system files and registry keys to proceed with deletion/wiping process. If the executables are\r\nopened as a user without UAC privilege elevation – the malware only wipes the files under C:\\Users and the\r\nsystem shuts down after.\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 6 of 11\n\nExhibit 12: Missing \\Boot\\BCD file (error)\r\nWhat eSentire is doing about it\r\nOur Threat Response Unit (TRU) combines threat intelligence gleaned from research, security incidents, and the\r\nexternal threat landscape to create actionable outcomes for our customers. We are taking a holistic response\r\napproach to combat modern destructive malware by deploying countermeasures, such as:\r\nDetections to identify and prevent Double Zero Wiper are in place across eSentire MDR for Endpoint and\r\nLog products\r\nThreat hunts have been performed for indicators associated with DoubleZero malware\r\nRecommendations from eSentire’s Threat Response Unit (TRU)\r\nWe recommend implementing the following controls to help secure your organization against the DoubleZero\r\nmalware:\r\nConfirm that all devices are protected with Endpoint Detection and Response (EDR) solutions\r\nImplement a Cyber Security Awareness Training Program that educates the employees about the threat\r\nlandscape\r\nEnsure the role-based access control (RBAC) that restricts system access to authorized users is in place\r\nImplement a Vulnerability Management Program that helps identify and prioritize high severity\r\nvulnerabilities.\r\nPatch any external-facing applications and devices as well as enforce strong password policies\r\nWhile the Tactics, Techniques, and Procedures (TTPs) used by adversaries grow in sophistication, they lead to a\r\nlimited set of choke points at which critical business decisions must be made. Intercepting the various attack paths\r\nutilized by the modern threat actor requires actively monitoring the threat landscape, developing, and deploying\r\nendpoint detection, and the ability to investigate logs \u0026 network data during active intrusions.\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 7 of 11\n\neSentire’s Threat Response Unit (TRU) is a world-class team of threat researchers who develop new detections\r\nenriched by original threat intelligence and leverage new machine learning models that correlate multi-signal data\r\nand automate rapid response to advanced threats.\r\nIf you’re not currently engaged with an MDR provider, eSentire MDR can help you reclaim the advantage and put\r\nyour business ahead of disruption.\r\nLearn what it means to have an elite team of Threat Hunters and Researchers that works for you. Connect with an\r\neSentire Security Specialist.\r\nAppendix\r\nSources\r\nhttps://cert.gov.ua/article/38088\r\nhttps://docs.microsoft.com/en-us/dotnet/api/\r\nIndicators of Compromise\r\nName File Hash (SHA-256)\r\nВирус... крайне\r\nопасно!!!.zip\r\nd897f07ae6f42de8f35e2b05f5ef5733d7ec599d5e786d3225e66ca605a48f53\r\ncsrss.zip 8dd8b9bd94de1e72f0c400c5f32dcefc114cc0a5bf14b74ba6edc19fd4aeb2a5\r\ncpcrs.exe (DoubleZero) 3b2e708eaa4744c76a633391cf2c983f4a098b46436525619e5ea44e105355fe\r\ncsrss.exe (DoubleZero) 30b3cbe8817ed75d8221059e4be35d5624bd6b5dc921d4991a7adc4c3eb5de4a\r\nYara Rules\r\nimport \"pe\"\r\nimport \"math\"\r\nrule DoubleZero {\r\n meta:\r\n author = \"eSentire TI\"\r\n date = \"03/24/2022\"\r\n version = \"1.0\"\r\n strings:\r\n $file = \"Microsoft.NET\" wide fullword nocase // .NET binary\r\n $api1 = \"NtFsControlFile\" // send a control code to the file system\r\n $api2 = \"CreateDecryptor\" // create the AES decryptor\r\n $api3 = \"set_UseShellExecute\" // use OS shell to start the process\r\n $api4 = \"FsctlSetZeroData\" // zero out the data\r\n $access_api1 = \"RtlAdjustPrivilege\" // modify the privileges\r\n $access_api2 = \"AddAccessRule\" // add a rule to the list of rules within a FileSystemSecurity object\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 8 of 11\n\ncondition:\r\n for any i in (0..pe.number_of_sections - 1): (\r\n math.entropy(pe.sections[i].raw_data_offset, pe.sections[i].raw_data_size) \u003e=4\r\n and pe.sections[i].name == \".text\" ) and\r\n all of ($api*) and all of ($access_api*) and $file and\r\n (uint16(0) == 0x5A4D or uint32(0) == 0x4464c457f)\r\n and filesize \u003c 500KB\r\n}\r\nTo learn how your organization can build cyber resilience and prevent business disruption with eSentire’s Next\r\nLevel MDR, connect with an eSentire Security Specialist now.\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 9 of 11\n\nGET STARTED\r\nABOUT ESENTIRE’S THREAT RESPONSE UNIT (TRU)\r\nThe eSentire Threat Response Unit (TRU) is an industry-leading threat research team committed to helping your\r\norganization become more resilient. TRU is an elite team of threat hunters and researchers that supports our 24/7\r\nSecurity Operations Centers (SOCs), builds threat detection models across the eSentire XDR Cloud Platform, and\r\nworks as an extension of your security team to continuously improve our Managed Detection and Response\r\nservice. By providing complete visibility across your attack surface and performing global threat sweeps and\r\nproactive hypothesis-driven threat hunts augmented by original threat research, we are laser-focused on defending\r\nyour organization against known and unknown threats.\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 10 of 11\n\nSource: https://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nhttps://www.esentire.com/blog/esentire-threat-intelligence-malware-analysis-doublezero\r\nPage 11 of 11",
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