Actor(s): Lazarus Group
SHADYCAT is a dropper and spreader component for the HERMES 2.1 RANSOMWARE radical edition.
rule win_bitsran_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2022-08-05" version = "1" description = "Detects win.bitsran." info = "autogenerated rule brought to you by yara-signator" tool = "yara-signator v0.6.0" signator_config = "callsandjumps;datarefs;binvalue" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.bitsran" malpedia_rule_date = "20220805" malpedia_hash = "6ec06c64bcfdbeda64eff021c766b4ce34542b71" malpedia_version = "20220808" malpedia_license = "CC BY-SA 4.0" malpedia_sharing = "TLP:WHITE" /* DISCLAIMER * The strings used in this rule have been automatically selected from the * disassembly of memory dumps and unpacked files, using YARA-Signator. * The code and documentation is published here: * https://github.com/fxb-cocacoding/yara-signator * As Malpedia is used as data source, please note that for a given * number of families, only single samples are documented. * This likely impacts the degree of generalization these rules will offer. * Take the described generation method also into consideration when you * apply the rules in your use cases and assign them confidence levels. */ strings: $sequence_0 = { c3 837df4fd 7516 8b560c 8b4328 8b4b24 52 } // n = 7, score = 100 // c3 | ret // 837df4fd | cmp dword ptr [ebp - 0xc], -3 // 7516 | jne 0x18 // 8b560c | mov edx, dword ptr [esi + 0xc] // 8b4328 | mov eax, dword ptr [ebx + 0x28] // 8b4b24 | mov ecx, dword ptr [ebx + 0x24] // 52 | push edx $sequence_1 = { 83c40c 894628 85c0 7521 8b5624 } // n = 5, score = 100 // 83c40c | add esp, 0xc // 894628 | mov dword ptr [esi + 0x28], eax // 85c0 | test eax, eax // 7521 | jne 0x23 // 8b5624 | mov edx, dword ptr [esi + 0x24] $sequence_2 = { 8b4e10 83c708 c7451000000000 0bc2 ba01000000 0155fc } // n = 6, score = 100 // 8b4e10 | mov ecx, dword ptr [esi + 0x10] // 83c708 | add edi, 8 // c7451000000000 | mov dword ptr [ebp + 0x10], 0 // 0bc2 | or eax, edx // ba01000000 | mov edx, 1 // 0155fc | add dword ptr [ebp - 4], edx $sequence_3 = { 6a01 8d55ff 6a01 52 e8???????? 83c410 83f801 } // n = 7, score = 100 // 6a01 | push 1 // 8d55ff | lea edx, [ebp - 1] // 6a01 | push 1 // 52 | push edx // e8???????? | // 83c410 | add esp, 0x10 // 83f801 | cmp eax, 1 $sequence_4 = { 894f04 8b450c 8bc8 2b0f } // n = 4, score = 100 // 894f04 | mov dword ptr [edi + 4], ecx // 8b450c | mov eax, dword ptr [ebp + 0xc] // 8bc8 | mov ecx, eax // 2b0f | sub ecx, dword ptr [edi] $sequence_5 = { 2bf2 3bf1 737c 33c9 eb7a 3bfa 7553 } // n = 7, score = 100 // 2bf2 | sub esi, edx // 3bf1 | cmp esi, ecx // 737c | jae 0x7e // 33c9 | xor ecx, ecx // eb7a | jmp 0x7c // 3bfa | cmp edi, edx // 7553 | jne 0x55 $sequence_6 = { c745fc99ffffff 83ceff 8b0b 8d45a8 50 51 e8???????? } // n = 7, score = 100 // c745fc99ffffff | mov dword ptr [ebp - 4], 0xffffff99 // 83ceff | or esi, 0xffffffff // 8b0b | mov ecx, dword ptr [ebx] // 8d45a8 | lea eax, [ebp - 0x58] // 50 | push eax // 51 | push ecx // e8???????? | $sequence_7 = { 0f877d010000 2bf3 c1fe02 3bfa 7557 8bc7 } // n = 6, score = 100 // 0f877d010000 | ja 0x183 // 2bf3 | sub esi, ebx // c1fe02 | sar esi, 2 // 3bfa | cmp edi, edx // 7557 | jne 0x59 // 8bc7 | mov eax, edi $sequence_8 = { 8d8de8faffff 51 8d95f4fdffff 52 ff15???????? 6803010000 8d85f1fcffff } // n = 7, score = 100 // 8d8de8faffff | lea ecx, [ebp - 0x518] // 51 | push ecx // 8d95f4fdffff | lea edx, [ebp - 0x20c] // 52 | push edx // ff15???????? | // 6803010000 | push 0x103 // 8d85f1fcffff | lea eax, [ebp - 0x30f] $sequence_9 = { 899d58fdffff 3bd9 0f83fe000000 3bd3 0f87f6000000 8b35???????? 2bda } // n = 7, score = 100 // 899d58fdffff | mov dword ptr [ebp - 0x2a8], ebx // 3bd9 | cmp ebx, ecx // 0f83fe000000 | jae 0x104 // 3bd3 | cmp edx, ebx // 0f87f6000000 | ja 0xfc // 8b35???????? | // 2bda | sub ebx, edx condition: 7 of them and filesize < 344064 }
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