rule win_ryuk_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-08-17"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.4.0"
        tool_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.ryuk"
        malpedia_rule_date = "20200817"
        malpedia_hash = "8c895fd01eccb47a6225bcb1a3ba53cbb98644c5"
        malpedia_version = "20200817"
        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 / approach 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 = { e8???????? e8???????? b9e8030000 ff15???????? }
            // n = 4, score = 700
            //   e8????????           |                     
            //   e8????????           |                     
            //   b9e8030000           | mov                 ecx, 0x3e8
            //   ff15????????         |                     

        $sequence_1 = { ff15???????? b803000000 eb05 b805000000 }
            // n = 4, score = 700
            //   ff15????????         |                     
            //   b803000000           | mov                 eax, 3
            //   eb05                 | jmp                 7
            //   b805000000           | mov                 eax, 5

        $sequence_2 = { ff15???????? b809000000 e9???????? 4533c9 }
            // n = 4, score = 600
            //   ff15????????         |                     
            //   b809000000           | push                edi
            //   e9????????           |                     
            //   4533c9               | dec                 eax

        $sequence_3 = { 498bc1 c3 4053 4883ec20 8bc1 }
            // n = 5, score = 600
            //   498bc1               | push                edi
            //   c3                   | dec                 eax
            //   4053                 | sub                 esp, 0x30
            //   4883ec20             | and                 dword ptr [esp + 0x20], 0
            //   8bc1                 | dec                 ecx

        $sequence_4 = { 4883c020 4883c428 c3 48895c2408 57 4883ec30 8364242000 }
            // n = 7, score = 600
            //   4883c020             | dec                 eax
            //   4883c428             | add                 eax, 0x20
            //   c3                   | dec                 eax
            //   48895c2408           | add                 esp, 0x28
            //   57                   | ret                 
            //   4883ec30             | dec                 eax
            //   8364242000           | mov                 dword ptr [esp + 8], ebx

        $sequence_5 = { 68???????? 6a01 6a00 6814010000 }
            // n = 4, score = 600
            //   68????????           |                     
            //   6a01                 | push                1
            //   6a00                 | push                0
            //   6814010000           | push                0x114

        $sequence_6 = { 488bc3 4883c430 5b c3 48895c2408 48896c2410 }
            // n = 6, score = 600
            //   488bc3               | sub                 esp, 0x30
            //   4883c430             | and                 dword ptr [esp + 0x20], 0
            //   5b                   | mov                 ecx, 8
            //   c3                   | mov                 eax, 9
            //   48895c2408           | inc                 ebp
            //   48896c2410           | xor                 ecx, ecx

        $sequence_7 = { 48897c2430 488d4c2440 c744242802000000 4533c9 4533c0 c744242002000000 ba000000c0 }
            // n = 7, score = 500
            //   48897c2430           | pop                 ebp
            //   488d4c2440           | ret                 
            //   c744242802000000     | push                8
            //   4533c9               | push                esi
            //   4533c0               | jne                 0x3a
            //   c744242002000000     | push                edi
            //   ba000000c0           | push                ebx

        $sequence_8 = { 85c0 7508 6a01 ff15???????? 68???????? 6a01 }
            // n = 6, score = 500
            //   85c0                 | test                eax, eax
            //   7508                 | jne                 0xa
            //   6a01                 | push                1
            //   ff15????????         |                     
            //   68????????           |                     
            //   6a01                 | push                1

        $sequence_9 = { 4885d2 7423 8078ff48 751d 803845 7518 80780152 }
            // n = 7, score = 500
            //   4885d2               | pop                 ebp
            //   7423                 | ret                 
            //   8078ff48             | mov                 edi, edi
            //   751d                 | ret                 4
            //   803845               | mov                 edi, edi
            //   7518                 | push                ebp
            //   80780152             | mov                 ebp, esp

        $sequence_10 = { ff15???????? 488bd8 ff15???????? 83f820 7510 488bcb }
            // n = 6, score = 500
            //   ff15????????         |                     
            //   488bd8               | sub                 esp, 0x30
            //   ff15????????         |                     
            //   83f820               | and                 dword ptr [esp + 0x20], 0
            //   7510                 | mov                 ecx, 8
            //   488bcb               | mov                 eax, 9

        $sequence_11 = { 41b900800000 4533c0 488bd6 488bcf ff15???????? }
            // n = 5, score = 500
            //   41b900800000         | mov                 edi, dword ptr [esp + 8]
            //   4533c0               | dec                 ecx
            //   488bd6               | mov                 eax, ecx
            //   488bcf               | ret                 
            //   ff15????????         |                     

        $sequence_12 = { 4533c0 c744242003000000 ba00000040 ff15???????? }
            // n = 4, score = 500
            //   4533c0               | jne                 0x32
            //   c744242003000000     | push                0x28
            //   ba00000040           | push                esi
            //   ff15????????         |                     

        $sequence_13 = { ff15???????? 448b442468 33d2 b9ffff1f00 ff15???????? }
            // n = 5, score = 500
            //   ff15????????         |                     
            //   448b442468           | push                edi
            //   33d2                 | test                eax, eax
            //   b9ffff1f00           | jne                 0x6a
            //   ff15????????         |                     

        $sequence_14 = { 8bc1 2bc2 d1e8 03c2 c1e806 6bc05a }
            // n = 6, score = 500
            //   8bc1                 | inc                 eax
            //   2bc2                 | push                ebx
            //   d1e8                 | dec                 eax
            //   03c2                 | sub                 esp, 0x20
            //   c1e806               | mov                 eax, ecx
            //   6bc05a               | dec                 eax

        $sequence_15 = { e9???????? 6a04 6800100000 6810270000 }
            // n = 4, score = 400
            //   e9????????           |                     
            //   6a04                 | push                4
            //   6800100000           | push                0x1000
            //   6810270000           | push                0x2710

        $sequence_16 = { 7407 48 85c0 7ff0 }
            // n = 4, score = 400
            //   7407                 | je                  9
            //   48                   | dec                 eax
            //   85c0                 | test                eax, eax
            //   7ff0                 | jg                  0xfffffff2

        $sequence_17 = { ff7508 e8???????? 5e 5d c3 6a08 68???????? }
            // n = 7, score = 400
            //   ff7508               | ret                 
            //   e8????????           |                     
            //   5e                   | inc                 eax
            //   5d                   | push                ebx
            //   c3                   | dec                 eax
            //   6a08                 | sub                 esp, 0x20
            //   68????????           |                     

        $sequence_18 = { 0f9fc0 5d c3 8bff 55 8bec 8b4508 }
            // n = 7, score = 400
            //   0f9fc0               | shr                 eax, 1
            //   5d                   | add                 eax, edx
            //   c3                   | shr                 eax, 6
            //   8bff                 | imul                eax, eax, 0x5a
            //   55                   | mul                 ecx
            //   8bec                 | mov                 eax, ecx
            //   8b4508               | sub                 eax, edx

        $sequence_19 = { 488d0d63080000 e8???????? e8???????? 8bc8 e8???????? 85c0 7556 }
            // n = 7, score = 400
            //   488d0d63080000       | dec                 eax
            //   e8????????           |                     
            //   e8????????           |                     
            //   8bc8                 | mov                 dword ptr [esp + 8], ebx
            //   e8????????           |                     
            //   85c0                 | push                edi
            //   7556                 | dec                 eax

        $sequence_20 = { c20400 8bff 55 8bec b8ffff0000 83ec18 66394508 }
            // n = 7, score = 400
            //   c20400               | pop                 ebx
            //   8bff                 | ret                 
            //   55                   | dec                 eax
            //   8bec                 | mov                 dword ptr [esp + 8], ebx
            //   b8ffff0000           | dec                 eax
            //   83ec18               | mov                 dword ptr [esp + 0x10], ebp
            //   66394508             | jmp                 6

        $sequence_21 = { e8???????? 84c0 746c e8???????? 488d0d63080000 e8???????? e8???????? }
            // n = 7, score = 400
            //   e8????????           |                     
            //   84c0                 | dec                 eax
            //   746c                 | mov                 dword ptr [esp + 0x10], ebp
            //   e8????????           |                     
            //   488d0d63080000       | ret                 
            //   e8????????           |                     
            //   e8????????           |                     

        $sequence_22 = { 8d7602 6685c9 75f1 5e 5d c3 8bff }
            // n = 7, score = 400
            //   8d7602               | add                 eax, edx
            //   6685c9               | shr                 eax, 6
            //   75f1                 | imul                eax, eax, 0x5a
            //   5e                   | mov                 eax, 0x6c16c16d
            //   5d                   | mul                 ecx
            //   c3                   | mov                 eax, ecx
            //   8bff                 | sub                 eax, edx

        $sequence_23 = { ff15???????? 56 ff15???????? be14010000 }
            // n = 4, score = 300
            //   ff15????????         |                     
            //   56                   | push                esi
            //   ff15????????         |                     
            //   be14010000           | mov                 esi, 0x114

        $sequence_24 = { 6a04 53 53 6800000040 56 ff15???????? 8bf8 }
            // n = 7, score = 300
            //   6a04                 | push                4
            //   53                   | push                ebx
            //   53                   | push                ebx
            //   6800000040           | push                0x40000000
            //   56                   | push                esi
            //   ff15????????         |                     
            //   8bf8                 | mov                 edi, eax

        $sequence_25 = { 6a00 ff15???????? 6a00 6a02 6a03 }
            // n = 5, score = 300
            //   6a00                 | shr                 eax, 1
            //   ff15????????         |                     
            //   6a00                 | add                 eax, edx
            //   6a02                 | shr                 eax, 6
            //   6a03                 | shr                 eax, 1

        $sequence_26 = { 85c0 751c 6a08 56 68???????? 57 53 }
            // n = 7, score = 300
            //   85c0                 | test                eax, eax
            //   751c                 | jne                 0x1e
            //   6a08                 | push                8
            //   56                   | push                esi
            //   68????????           |                     
            //   57                   | push                edi
            //   53                   | push                ebx

        $sequence_27 = { 6a08 6a18 68???????? 68???????? 68???????? ff15???????? 85c0 }
            // n = 7, score = 300
            //   6a08                 | jne                 0x12
            //   6a18                 | dec                 eax
            //   68????????           |                     
            //   68????????           |                     
            //   68????????           |                     
            //   ff15????????         |                     
            //   85c0                 | mov                 ecx, ebx

        $sequence_28 = { 53 ff15???????? 85c0 7554 6a10 56 68???????? }
            // n = 7, score = 300
            //   53                   | push                ebx
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   7554                 | jne                 0x56
            //   6a10                 | push                0x10
            //   56                   | push                esi
            //   68????????           |                     

        $sequence_29 = { 8d0c49 c1e103 51 6a00 }
            // n = 4, score = 200
            //   8d0c49               | lea                 ecx, [ecx + ecx*2]
            //   c1e103               | shl                 ecx, 3
            //   51                   | push                ecx
            //   6a00                 | push                0

        $sequence_30 = { ba01000000 d1e2 8b45d0 0fb60c10 b8ff000000 2bc1 c1e008 }
            // n = 7, score = 200
            //   ba01000000           | mov                 ebp, esp
            //   d1e2                 | mov                 eax, 0xffff
            //   8b45d0               | sub                 esp, 0x18
            //   0fb60c10             | cmp                 word ptr [ebp + 8], ax
            //   b8ff000000           | pop                 edi
            //   2bc1                 | pop                 ebp
            //   c1e008               | ret                 4

        $sequence_31 = { 6a0a c1e818 51 50 }
            // n = 4, score = 200
            //   6a0a                 | push                0xa
            //   c1e818               | shr                 eax, 0x18
            //   51                   | push                ecx
            //   50                   | push                eax

        $sequence_32 = { 57 ff15???????? b80c000000 5f 5e }
            // n = 5, score = 200
            //   57                   | push                edi
            //   ff15????????         |                     
            //   b80c000000           | mov                 eax, 0xc
            //   5f                   | pop                 edi
            //   5e                   | pop                 esi

        $sequence_33 = { 51 6a00 ffd6 6800400000 }
            // n = 4, score = 200
            //   51                   | push                ecx
            //   6a00                 | push                0
            //   ffd6                 | call                esi
            //   6800400000           | push                0x4000

        $sequence_34 = { 2bf0 33c0 66890473 83ffff }
            // n = 4, score = 200
            //   2bf0                 | sub                 esi, eax
            //   33c0                 | xor                 eax, eax
            //   66890473             | mov                 word ptr [ebx + esi*2], ax
            //   83ffff               | cmp                 edi, -1

        $sequence_35 = { 0f85a2000000 8b01 6a00 ff75e4 8b4004 ff75dc 8b4c0838 }
            // n = 7, score = 100
            //   0f85a2000000         | jne                 0xa8
            //   8b01                 | mov                 eax, dword ptr [ecx]
            //   6a00                 | push                0
            //   ff75e4               | push                dword ptr [ebp - 0x1c]
            //   8b4004               | mov                 eax, dword ptr [eax + 4]
            //   ff75dc               | push                dword ptr [ebp - 0x24]
            //   8b4c0838             | mov                 ecx, dword ptr [eax + ecx + 0x38]

        $sequence_36 = { 7d0a 8a80b0ea4300 8803 43 47 8b0e c6459f01 }
            // n = 7, score = 100
            //   7d0a                 | jge                 0xc
            //   8a80b0ea4300         | mov                 al, byte ptr [eax + 0x43eab0]
            //   8803                 | mov                 byte ptr [ebx], al
            //   43                   | inc                 ebx
            //   47                   | inc                 edi
            //   8b0e                 | mov                 ecx, dword ptr [esi]
            //   c6459f01             | mov                 byte ptr [ebp - 0x61], 1

        $sequence_37 = { 7408 3a81206a4300 7542 8b07 8a10 }
            // n = 5, score = 100
            //   7408                 | je                  0xa
            //   3a81206a4300         | cmp                 al, byte ptr [ecx + 0x436a20]
            //   7542                 | jne                 0x44
            //   8b07                 | mov                 eax, dword ptr [edi]
            //   8a10                 | mov                 dl, byte ptr [eax]

    condition:
        7 of them and filesize < 7450624
}