Ransomware.
rule win_cuba_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.cuba." 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.cuba" malpedia_rule_date = "20260105" malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79" malpedia_version = "20251219" 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 = { 85c0 7810 3de4000000 7309 8b04c510704100 5d } // n = 6, score = 100 // 85c0 | test eax, eax // 7810 | js 0x12 // 3de4000000 | cmp eax, 0xe4 // 7309 | jae 0xb // 8b04c510704100 | mov eax, dword ptr [eax*8 + 0x417010] // 5d | pop ebp $sequence_1 = { c3 8bff 55 8bec 8b4d08 33c0 3b0cc5905d4100 } // n = 7, score = 100 // c3 | ret // 8bff | mov edi, edi // 55 | push ebp // 8bec | mov ebp, esp // 8b4d08 | mov ecx, dword ptr [ebp + 8] // 33c0 | xor eax, eax // 3b0cc5905d4100 | cmp ecx, dword ptr [eax*8 + 0x415d90] $sequence_2 = { 0019 43 41 00444341 } // n = 4, score = 100 // 0019 | add byte ptr [ecx], bl // 43 | inc ebx // 41 | inc ecx // 00444341 | add byte ptr [ebx + eax*2 + 0x41], al $sequence_3 = { 8bd6 c745ac749f4100 8bce 0fb707 } // n = 4, score = 100 // 8bd6 | mov edx, esi // c745ac749f4100 | mov dword ptr [ebp - 0x54], 0x419f74 // 8bce | mov ecx, esi // 0fb707 | movzx eax, word ptr [edi] $sequence_4 = { 000d???????? 384100 b538 41 } // n = 4, score = 100 // 000d???????? | // 384100 | cmp byte ptr [ecx], al // b538 | mov ch, 0x38 // 41 | inc ecx $sequence_5 = { 0026 45 41 003a } // n = 4, score = 100 // 0026 | add byte ptr [esi], ah // 45 | inc ebp // 41 | inc ecx // 003a | add byte ptr [edx], bh $sequence_6 = { 0026 43 41 00b043410062 } // n = 4, score = 100 // 0026 | add byte ptr [esi], ah // 43 | inc ebx // 41 | inc ecx // 00b043410062 | add byte ptr [eax + 0x62004143], dh $sequence_7 = { 0012 45 41 0026 } // n = 4, score = 100 // 0012 | add byte ptr [edx], dl // 45 | inc ebp // 41 | inc ecx // 0026 | add byte ptr [esi], ah $sequence_8 = { 83e801 0f8501010000 c745e004934100 8b4508 } // n = 4, score = 100 // 83e801 | sub eax, 1 // 0f8501010000 | jne 0x107 // c745e004934100 | mov dword ptr [ebp - 0x20], 0x419304 // 8b4508 | mov eax, dword ptr [ebp + 8] $sequence_9 = { ff24953c354000 c7878c00000001000000 85c9 747e 3bc6 730a } // n = 6, score = 100 // ff24953c354000 | jmp dword ptr [edx*4 + 0x40353c] // c7878c00000001000000 | mov dword ptr [edi + 0x8c], 1 // 85c9 | test ecx, ecx // 747e | je 0x80 // 3bc6 | cmp eax, esi // 730a | jae 0xc $sequence_10 = { 660fc5c400 25f0070000 660f28a040974100 660f28b830934100 660f54f0 660f5cc6 660f59f4 } // n = 7, score = 100 // 660fc5c400 | pextrw eax, xmm4, 0 // 25f0070000 | and eax, 0x7f0 // 660f28a040974100 | movapd xmm4, xmmword ptr [eax + 0x419740] // 660f28b830934100 | movapd xmm7, xmmword ptr [eax + 0x419330] // 660f54f0 | andpd xmm6, xmm0 // 660f5cc6 | subpd xmm0, xmm6 // 660f59f4 | mulpd xmm6, xmm4 $sequence_11 = { ffd7 85c0 750c e8???????? 5f } // n = 5, score = 100 // ffd7 | call edi // 85c0 | test eax, eax // 750c | jne 0xe // e8???????? | // 5f | pop edi $sequence_12 = { 000c43 41 0035???????? 43 } // n = 4, score = 100 // 000c43 | add byte ptr [ebx + eax*2], cl // 41 | inc ecx // 0035???????? | // 43 | inc ebx $sequence_13 = { 003a 45 41 004245 } // n = 4, score = 100 // 003a | add byte ptr [edx], bh // 45 | inc ebp // 41 | inc ecx // 004245 | add byte ptr [edx + 0x45], al $sequence_14 = { 7414 8d85c0f9ffff 50 56 ff15???????? 85c0 75e6 } // n = 7, score = 100 // 7414 | je 0x16 // 8d85c0f9ffff | lea eax, [ebp - 0x640] // 50 | push eax // 56 | push esi // ff15???????? | // 85c0 | test eax, eax // 75e6 | jne 0xffffffe8 $sequence_15 = { 000446 41 00d1 45 } // n = 4, score = 100 // 000446 | add byte ptr [esi + eax*2], al // 41 | inc ecx // 00d1 | add cl, dl // 45 | inc ebp condition: 7 of them and filesize < 1094656 }
rule win_cuba_w0 { meta: description = "Detect_cuba_ransomware" author = "@malgamy12" date = "24/11/2022" license = "DRL 1.1" hash = "c2aad237b3f4c5a55df88ef26c25899fc4ec8170" hash = "4b41a1508f0f519396b7c14df161954f1c819e86" hash = "d5fe48b914c83711fe5313a4aaf1e8d80533543d" hash = "159b566e62dcec608a3991100d6edbca781d48c0" hash = "e1cae0d2a320a2756ae1ee5d37bfe803b39853fa" hash = "6f1d355b95546f0a5a09f7fd0b85fc9658e87813" hash = "25da0849207beb5695c8d9826b585b8cda435eba" hash = "3997d19f38ce14b7643c1ad8d6a737990b444215" hash = "f008e568c313b6f41406658a77313f89df07017e" hash = "7e42b668fd2ca96b05f39d5097943a191f1010f4" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.cuba" malpedia_rule_date = "20230118" malpedia_hash = "" malpedia_version = "20230118" malpedia_license = "DRL 1.1" malpedia_sharing = "TLP:WHITE" strings: $p1 = {C1 8D 73 ?? 99 83 E2 ?? 03 C2 C1 F8 ?? 8D 04 45 [4] 89 83 [4] 0F B6 0F 0F B6 47 ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 89 0B 0F B6 47 ?? 89 4D ?? 0F B6 4F ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 89 0E 0F B6 4F ?? 0F B6 47 ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 89 4B ?? 0F B6 4F ?? 0F B6 47 ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 0F B6 47 ?? C1 E1 ?? 0B C8 8B 45 ?? 89 4D ?? 89 4B} $p2 = {5D ?? 8B C3 C1 E8 ?? 0F B6 D0 8B C3 C1 E8 ?? 0F B6 C8 8B 04 95 [4] 33 04 8D [4] 8B CB C1 E9 ?? 33 04 8D [4] 0F B6 CB 5B 33 04 8D} $p3 = {8B 75 ?? 8B C6 C1 E8 ?? 0F B6 C8 8B 45 ?? C1 E8 ?? 0F B6 C0 8B 0C 8D [4] 8B 55 ?? 33 0C 85 [4] 8B C2 C1 E8 ?? 33 0C 85 [4] 8B 45 ?? 0F B6 C0 33 0C 85 [4] 33 0F 8B 45 ?? C1 E8 ?? 89 4D ?? 0F B6 C8 8B C6 C1 E8 ?? 0F B6 C0 8B 0C 8D [4] 33 0C 85 [4] 8B 45 ?? C1 E8 ?? 33 0C 85 [4] 0F B6 C2 33 0C 85 [4] 33 4F ?? 8B 45 ?? C1 E8 ?? 89 4D ?? 0F B6 C8 8B C2 C1 E8 ?? 0F B6 C0 C1 EA ?? 8B 1C 8D [4] 8B 4D ?? 33 1C 85 [4] 8B C6 C1 E8 ?? 33 1C 85 [4] 0F B6 C1 C1 E9 ?? 0F B6 C9 33 1C 85 [4] 33 5F ?? 0F B6 C2 8B 14 8D [4] 33 14 85 [4] 8B 45 ?? C1 E8 ?? 33 14 85 [4] 8B C6 0F B6 C0 33 14 85 [4] 8B C3 33 57 ?? C1 E8 ?? 0F B6 C8 8B 45 ?? C1 E8 ?? 0F B6 C0 8B 0C 8D [4] 33 0C 85 [4] 8B 45 ?? C1 E8 ?? 33 0C 85 [4] 0F B6 C2 33 0C 85 [4] 8B C2 33 4F ?? C1 E8 ?? 89 4D ?? 0F B6 C8 8B C3 C1 E8 ?? 8B 0C 8D [4] 0F B6 C0 33 0C 85 [4] 8B 45 ?? C1 E8 ?? 33 0C 85 [4] 8B 45 ?? 0F B6 C0 33 0C 85 [4] 8B C2 33 4F ?? C1 E8 ?? 89 4D ?? 0F B6 C8 8B 45 ?? C1 E8 ?? 0F B6 C0 8B 0C 8D [4] C1 EA ?? 33 0C 85 [4] 8B C3 C1 E8 ?? 33 0C 85 [4] 89 4D ?? 8B 4D ?? 8B 75 ?? 0F B6 C1 C1 E9 ?? 0F B6 C9 33 34 85 [4] 8B C6 89 75 ?? 33 47 ?? 8B 0C 8D [4] 89 45 ?? 8B 45 ?? C1 E8 ?? 0F B6 C0 33 0C 85 [4] 33 0C 95 [4] 0F B6 C3 33 0C 85 [4] 33 4F ?? 83 C7 ?? 83 6D} condition: uint16(0) == 0x5A4D and all of them }
If your designated proposal does not fit in any other category, feel free to write a free-text in the comment field below. Changes regarding references should be proposed on the Malpedia library page.
Your suggestion will be reviewed before being published. Thank you for contributing!
YYYY-MM-DD
YYYY-MM
YYYY