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 = "2023-03-28" 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 = "20230328" malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d" malpedia_version = "20230407" 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 = { 8985ecfeffff 898568ffffff 898560ffffff 3b8d5cffffff 0f8f11030000 8bb54cffffff } // n = 6, score = 100 // 8985ecfeffff | mov dword ptr [ebp - 0x114], eax // 898568ffffff | mov dword ptr [ebp - 0x98], eax // 898560ffffff | mov dword ptr [ebp - 0xa0], eax // 3b8d5cffffff | cmp ecx, dword ptr [ebp - 0xa4] // 0f8f11030000 | jg 0x317 // 8bb54cffffff | mov esi, dword ptr [ebp - 0xb4] $sequence_1 = { 5d c3 8bc7 5f 5b 5e 5d } // n = 7, score = 100 // 5d | pop ebp // c3 | ret // 8bc7 | mov eax, edi // 5f | pop edi // 5b | pop ebx // 5e | pop esi // 5d | pop ebp $sequence_2 = { 8945f4 8945f8 8d85ecfbffff 50 e8???????? 6800040000 8d8decf3ffff } // n = 7, score = 100 // 8945f4 | mov dword ptr [ebp - 0xc], eax // 8945f8 | mov dword ptr [ebp - 8], eax // 8d85ecfbffff | lea eax, [ebp - 0x414] // 50 | push eax // e8???????? | // 6800040000 | push 0x400 // 8d8decf3ffff | lea ecx, [ebp - 0xc14] $sequence_3 = { 83ffff 0f8460010000 8d85c0f6ffff 50 57 e8???????? } // n = 6, score = 100 // 83ffff | cmp edi, -1 // 0f8460010000 | je 0x166 // 8d85c0f6ffff | lea eax, [ebp - 0x940] // 50 | push eax // 57 | push edi // e8???????? | $sequence_4 = { 33c5 8945fc 8b4508 668bc8 66c1e909 babc070000 6603ca } // n = 7, score = 100 // 33c5 | xor eax, ebp // 8945fc | mov dword ptr [ebp - 4], eax // 8b4508 | mov eax, dword ptr [ebp + 8] // 668bc8 | mov cx, ax // 66c1e909 | shr cx, 9 // babc070000 | mov edx, 0x7bc // 6603ca | add cx, dx $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 = { 8bcf 2b0d???????? b8398ee338 c1f902 f7e1 d1ea 8d4301 } // n = 7, score = 100 // 8bcf | mov ecx, edi // 2b0d???????? | // b8398ee338 | mov eax, 0x38e38e39 // c1f902 | sar ecx, 2 // f7e1 | mul ecx // d1ea | shr edx, 1 // 8d4301 | lea eax, [ebx + 1] $sequence_7 = { d3e8 8b4dec 8b148d20454100 23d0 0155f0 d3e8 } // n = 6, score = 100 // d3e8 | shr eax, cl // 8b4dec | mov ecx, dword ptr [ebp - 0x14] // 8b148d20454100 | mov edx, dword ptr [ecx*4 + 0x414520] // 23d0 | and edx, eax // 0155f0 | add dword ptr [ebp - 0x10], edx // d3e8 | shr eax, cl $sequence_8 = { 8b4df4 d3e8 8b4dec 8b148d20454100 23d0 0155f0 } // n = 6, score = 100 // 8b4df4 | mov ecx, dword ptr [ebp - 0xc] // d3e8 | shr eax, cl // 8b4dec | mov ecx, dword ptr [ebp - 0x14] // 8b148d20454100 | mov edx, dword ptr [ecx*4 + 0x414520] // 23d0 | and edx, eax // 0155f0 | add dword ptr [ebp - 0x10], edx $sequence_9 = { 807e0100 0f84ba000000 8b4e0c 8b5604 6a00 } // n = 5, score = 100 // 807e0100 | cmp byte ptr [esi + 1], 0 // 0f84ba000000 | je 0xc0 // 8b4e0c | mov ecx, dword ptr [esi + 0xc] // 8b5604 | mov edx, dword ptr [esi + 4] // 6a00 | push 0 condition: 7 of them and filesize < 344064 }
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