rule win_avcrypt_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.avcrypt."
        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.avcrypt"
        malpedia_rule_date = "20230124"
        malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686"
        malpedia_version = "20230125"
        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 = { 2b1f d50c 7b90 1e 56 82de82 54 }
            // n = 7, score = 100
            //   2b1f                 | sub                 ebx, dword ptr [edi]
            //   d50c                 | aad                 0xc
            //   7b90                 | jnp                 0xffffff92
            //   1e                   | push                ds
            //   56                   | push                esi
            //   82de82               | sbb                 dh, 0x82
            //   54                   | push                esp

        $sequence_1 = { 83ec18 c645fc0d 8bcc 57 e8???????? c645fc0a e8???????? }
            // n = 7, score = 100
            //   83ec18               | sub                 esp, 0x18
            //   c645fc0d             | mov                 byte ptr [ebp - 4], 0xd
            //   8bcc                 | mov                 ecx, esp
            //   57                   | push                edi
            //   e8????????           |                     
            //   c645fc0a             | mov                 byte ptr [ebp - 4], 0xa
            //   e8????????           |                     

        $sequence_2 = { 7ed0 83c8ff eb07 8b04f5d4c94200 5f 5e }
            // n = 6, score = 100
            //   7ed0                 | jle                 0xffffffd2
            //   83c8ff               | or                  eax, 0xffffffff
            //   eb07                 | jmp                 9
            //   8b04f5d4c94200       | mov                 eax, dword ptr [esi*8 + 0x42c9d4]
            //   5f                   | pop                 edi
            //   5e                   | pop                 esi

        $sequence_3 = { 8bcc 8965d4 68???????? e8???????? 83ec18 c645fc25 8bcc }
            // n = 7, score = 100
            //   8bcc                 | mov                 ecx, esp
            //   8965d4               | mov                 dword ptr [ebp - 0x2c], esp
            //   68????????           |                     
            //   e8????????           |                     
            //   83ec18               | sub                 esp, 0x18
            //   c645fc25             | mov                 byte ptr [ebp - 4], 0x25
            //   8bcc                 | mov                 ecx, esp

        $sequence_4 = { ff5108 ff15???????? 84db 7407 68???????? eb05 68???????? }
            // n = 7, score = 100
            //   ff5108               | call                dword ptr [ecx + 8]
            //   ff15????????         |                     
            //   84db                 | test                bl, bl
            //   7407                 | je                  9
            //   68????????           |                     
            //   eb05                 | jmp                 7
            //   68????????           |                     

        $sequence_5 = { ebc6 8b0c9580b54300 8a441904 a840 7508 0c02 88441904 }
            // n = 7, score = 100
            //   ebc6                 | jmp                 0xffffffc8
            //   8b0c9580b54300       | mov                 ecx, dword ptr [edx*4 + 0x43b580]
            //   8a441904             | mov                 al, byte ptr [ecx + ebx + 4]
            //   a840                 | test                al, 0x40
            //   7508                 | jne                 0xa
            //   0c02                 | or                  al, 2
            //   88441904             | mov                 byte ptr [ecx + ebx + 4], al

        $sequence_6 = { b8???????? e8???????? 8bf1 33ff 89b5e0f7ffff 89bde4f7ffff }
            // n = 6, score = 100
            //   b8????????           |                     
            //   e8????????           |                     
            //   8bf1                 | mov                 esi, ecx
            //   33ff                 | xor                 edi, edi
            //   89b5e0f7ffff         | mov                 dword ptr [ebp - 0x820], esi
            //   89bde4f7ffff         | mov                 dword ptr [ebp - 0x81c], edi

        $sequence_7 = { c645fc0e 8bcc 8965a0 57 e8???????? 83ec18 c645fc0f }
            // n = 7, score = 100
            //   c645fc0e             | mov                 byte ptr [ebp - 4], 0xe
            //   8bcc                 | mov                 ecx, esp
            //   8965a0               | mov                 dword ptr [ebp - 0x60], esp
            //   57                   | push                edi
            //   e8????????           |                     
            //   83ec18               | sub                 esp, 0x18
            //   c645fc0f             | mov                 byte ptr [ebp - 4], 0xf

        $sequence_8 = { 7416 56 56 56 8d45ec 50 56 }
            // n = 7, score = 100
            //   7416                 | je                  0x18
            //   56                   | push                esi
            //   56                   | push                esi
            //   56                   | push                esi
            //   8d45ec               | lea                 eax, [ebp - 0x14]
            //   50                   | push                eax
            //   56                   | push                esi

        $sequence_9 = { 897dfc 50 c7458044000000 e8???????? 83c40c 8d4dd8 }
            // n = 6, score = 100
            //   897dfc               | mov                 dword ptr [ebp - 4], edi
            //   50                   | push                eax
            //   c7458044000000       | mov                 dword ptr [ebp - 0x80], 0x44
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   8d4dd8               | lea                 ecx, [ebp - 0x28]

    condition:
        7 of them and filesize < 6160384
}