Ransomware.
rule win_cuba_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-09-17" 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 = "20260916" malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6" malpedia_version = "20260917" 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 = { 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_1 = { 84c0 0f8414010000 8b06 813846494445 750d 8178044c2e4341 0f84fd000000 } // n = 7, score = 100 // 84c0 | test al, al // 0f8414010000 | je 0x11a // 8b06 | mov eax, dword ptr [esi] // 813846494445 | cmp dword ptr [eax], 0x45444946 // 750d | jne 0xf // 8178044c2e4341 | cmp dword ptr [eax + 4], 0x41432e4c // 0f84fd000000 | je 0x103 $sequence_2 = { 3985c8f9ffff 7414 8d85c0f9ffff 50 56 ff15???????? } // n = 6, score = 100 // 3985c8f9ffff | cmp dword ptr [ebp - 0x638], eax // 7414 | je 0x16 // 8d85c0f9ffff | lea eax, [ebp - 0x640] // 50 | push eax // 56 | push esi // ff15???????? | $sequence_3 = { 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_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 = { 5e 7426 6683bdf4fdffff00 741c 8d85f4fdffff } // n = 5, score = 100 // 5e | pop esi // 7426 | je 0x28 // 6683bdf4fdffff00 | cmp word ptr [ebp - 0x20c], 0 // 741c | je 0x1e // 8d85f4fdffff | lea eax, [ebp - 0x20c] $sequence_6 = { ff15???????? eb16 39bdc8f9ffff 7414 8d85c0f9ffff } // n = 5, score = 100 // ff15???????? | // eb16 | jmp 0x18 // 39bdc8f9ffff | cmp dword ptr [ebp - 0x638], edi // 7414 | je 0x16 // 8d85c0f9ffff | lea eax, [ebp - 0x640] $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 = { 8945f0 8b450c 8945f4 8b4514 40 c745ecac9c4000 894df8 } // n = 7, score = 100 // 8945f0 | mov dword ptr [ebp - 0x10], eax // 8b450c | mov eax, dword ptr [ebp + 0xc] // 8945f4 | mov dword ptr [ebp - 0xc], eax // 8b4514 | mov eax, dword ptr [ebp + 0x14] // 40 | inc eax // c745ecac9c4000 | mov dword ptr [ebp - 0x14], 0x409cac // 894df8 | mov dword ptr [ebp - 8], ecx $sequence_9 = { 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_10 = { 8bce e8???????? e8???????? 8b4dfc 33c0 33cd 5e } // n = 7, score = 100 // 8bce | mov ecx, esi // e8???????? | // e8???????? | // 8b4dfc | mov ecx, dword ptr [ebp - 4] // 33c0 | xor eax, eax // 33cd | xor ecx, ebp // 5e | pop esi $sequence_11 = { 8b85e0feffff 03b40518ffffff 03b0fcb14100 03b5f8feffff } // n = 4, score = 100 // 8b85e0feffff | mov eax, dword ptr [ebp - 0x120] // 03b40518ffffff | add esi, dword ptr [ebp + eax - 0xe8] // 03b0fcb14100 | add esi, dword ptr [eax + 0x41b1fc] // 03b5f8feffff | add esi, dword ptr [ebp - 0x108] $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 = { 03f0 8b85e0feffff 03b40514ffffff 03b0f8b14100 03b5e4feffff 8d0433 } // n = 6, score = 100 // 03f0 | add esi, eax // 8b85e0feffff | mov eax, dword ptr [ebp - 0x120] // 03b40514ffffff | add esi, dword ptr [ebp + eax - 0xec] // 03b0f8b14100 | add esi, dword ptr [eax + 0x41b1f8] // 03b5e4feffff | add esi, dword ptr [ebp - 0x11c] // 8d0433 | lea eax, [ebx + esi] $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 }
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