rule win_teslacrypt_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-08-05"
        version = "1"
        description = "Detects win.teslacrypt."
        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.teslacrypt"
        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 = { 334500 335d04 334d08 33550c 81ffa0000000 0f8452030000 }
            // n = 6, score = 900
            //   334500               | xor                 eax, dword ptr [ebp]
            //   335d04               | xor                 ebx, dword ptr [ebp + 4]
            //   334d08               | xor                 ecx, dword ptr [ebp + 8]
            //   33550c               | xor                 edx, dword ptr [ebp + 0xc]
            //   81ffa0000000         | cmp                 edi, 0xa0
            //   0f8452030000         | je                  0x358

        $sequence_1 = { 33550c 81ffa0000000 0f8456030000 81ffc0000000 0f84ae010000 }
            // n = 5, score = 900
            //   33550c               | xor                 edx, dword ptr [ebp + 0xc]
            //   81ffa0000000         | cmp                 edi, 0xa0
            //   0f8456030000         | je                  0x35c
            //   81ffc0000000         | cmp                 edi, 0xc0
            //   0f84ae010000         | je                  0x1b4

        $sequence_2 = { 51 52 8b5530 0fb6c8 }
            // n = 4, score = 900
            //   51                   | push                ecx
            //   52                   | push                edx
            //   8b5530               | mov                 edx, dword ptr [ebp + 0x30]
            //   0fb6c8               | movzx               ecx, al

        $sequence_3 = { 55 53 56 57 8b6c2418 c785f0000000e0000000 8b5c2414 }
            // n = 7, score = 900
            //   55                   | push                ebp
            //   53                   | push                ebx
            //   56                   | push                esi
            //   57                   | push                edi
            //   8b6c2418             | mov                 ebp, dword ptr [esp + 0x18]
            //   c785f0000000e0000000     | mov    dword ptr [ebp + 0xf0], 0xe0
            //   8b5c2414             | mov                 ebx, dword ptr [esp + 0x14]

        $sequence_4 = { 33550c 81ffa0000000 0f8452030000 81ffc0000000 0f84ac010000 81ffe0000000 740a }
            // n = 7, score = 900
            //   33550c               | xor                 edx, dword ptr [ebp + 0xc]
            //   81ffa0000000         | cmp                 edi, 0xa0
            //   0f8452030000         | je                  0x358
            //   81ffc0000000         | cmp                 edi, 0xc0
            //   0f84ac010000         | je                  0x1b2
            //   81ffe0000000         | cmp                 edi, 0xe0
            //   740a                 | je                  0xc

        $sequence_5 = { 52 89f2 c1c808 0fb6c8 }
            // n = 4, score = 900
            //   52                   | push                edx
            //   89f2                 | mov                 edx, esi
            //   c1c808               | ror                 eax, 8
            //   0fb6c8               | movzx               ecx, al

        $sequence_6 = { 31d3 c1e810 c1e910 0fb6d1 }
            // n = 4, score = 900
            //   31d3                 | xor                 ebx, edx
            //   c1e810               | shr                 eax, 0x10
            //   c1e910               | shr                 ecx, 0x10
            //   0fb6d1               | movzx               edx, cl

        $sequence_7 = { 31d3 89e8 5d 334500 335d04 }
            // n = 5, score = 900
            //   31d3                 | xor                 ebx, edx
            //   89e8                 | mov                 eax, ebp
            //   5d                   | pop                 ebp
            //   334500               | xor                 eax, dword ptr [ebp]
            //   335d04               | xor                 ebx, dword ptr [ebp + 4]

        $sequence_8 = { 0f8467010000 8b442444 8b4c2448 8b54244c 8b742464 }
            // n = 5, score = 100
            //   0f8467010000         | je                  0x16d
            //   8b442444             | mov                 eax, dword ptr [esp + 0x44]
            //   8b4c2448             | mov                 ecx, dword ptr [esp + 0x48]
            //   8b54244c             | mov                 edx, dword ptr [esp + 0x4c]
            //   8b742464             | mov                 esi, dword ptr [esp + 0x64]

        $sequence_9 = { 8b4c2434 8d1536304b00 891424 8944241c 894c2418 e8???????? }
            // n = 6, score = 100
            //   8b4c2434             | mov                 ecx, dword ptr [esp + 0x34]
            //   8d1536304b00         | lea                 edx, [0x4b3036]
            //   891424               | mov                 dword ptr [esp], edx
            //   8944241c             | mov                 dword ptr [esp + 0x1c], eax
            //   894c2418             | mov                 dword ptr [esp + 0x18], ecx
            //   e8????????           |                     

        $sequence_10 = { 8b742438 39f0 89542404 7222 8b442418 6bc828 8b542428 }
            // n = 7, score = 100
            //   8b742438             | mov                 esi, dword ptr [esp + 0x38]
            //   39f0                 | cmp                 eax, esi
            //   89542404             | mov                 dword ptr [esp + 4], edx
            //   7222                 | jb                  0x24
            //   8b442418             | mov                 eax, dword ptr [esp + 0x18]
            //   6bc828               | imul                ecx, eax, 0x28
            //   8b542428             | mov                 edx, dword ptr [esp + 0x28]

        $sequence_11 = { 894c2414 89542410 7d23 8b442410 25ffff0000 89e1 894104 }
            // n = 7, score = 100
            //   894c2414             | mov                 dword ptr [esp + 0x14], ecx
            //   89542410             | mov                 dword ptr [esp + 0x10], edx
            //   7d23                 | jge                 0x25
            //   8b442410             | mov                 eax, dword ptr [esp + 0x10]
            //   25ffff0000           | and                 eax, 0xffff
            //   89e1                 | mov                 ecx, esp
            //   894104               | mov                 dword ptr [ecx + 4], eax

        $sequence_12 = { eb25 8b442464 8b4c2410 01c8 83c002 89e2 894204 }
            // n = 7, score = 100
            //   eb25                 | jmp                 0x27
            //   8b442464             | mov                 eax, dword ptr [esp + 0x64]
            //   8b4c2410             | mov                 ecx, dword ptr [esp + 0x10]
            //   01c8                 | add                 eax, ecx
            //   83c002               | add                 eax, 2
            //   89e2                 | mov                 edx, esp
            //   894204               | mov                 dword ptr [edx + 4], eax

        $sequence_13 = { 89442464 8b442450 a3???????? 8b484c 890c24 e8???????? b901000000 }
            // n = 7, score = 100
            //   89442464             | mov                 dword ptr [esp + 0x64], eax
            //   8b442450             | mov                 eax, dword ptr [esp + 0x50]
            //   a3????????           |                     
            //   8b484c               | mov                 ecx, dword ptr [eax + 0x4c]
            //   890c24               | mov                 dword ptr [esp], ecx
            //   e8????????           |                     
            //   b901000000           | mov                 ecx, 1

        $sequence_14 = { 83fe00 8944243c 894c2438 89542434 897c2430 }
            // n = 5, score = 100
            //   83fe00               | cmp                 esi, 0
            //   8944243c             | mov                 dword ptr [esp + 0x3c], eax
            //   894c2438             | mov                 dword ptr [esp + 0x38], ecx
            //   89542434             | mov                 dword ptr [esp + 0x34], edx
            //   897c2430             | mov                 dword ptr [esp + 0x30], edi

        $sequence_15 = { 56 8b442408 31c9 8b503c }
            // n = 4, score = 100
            //   56                   | push                esi
            //   8b442408             | mov                 eax, dword ptr [esp + 8]
            //   31c9                 | xor                 ecx, ecx
            //   8b503c               | mov                 edx, dword ptr [eax + 0x3c]

    condition:
        7 of them and filesize < 1187840
}