rule win_microbackdoor_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.microbackdoor."
        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.microbackdoor"
        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 = { 50 56 66894dd8 ff15???????? 85c0 }
            // n = 5, score = 100
            //   50                   | dec                 edx
            //   56                   | or                  edx, 0xffffff00
            //   66894dd8             | inc                 edx
            //   ff15????????         |                     
            //   85c0                 | dec                 eax

        $sequence_1 = { 7cdd 33c0 40 5f 5e 5b }
            // n = 6, score = 100
            //   7cdd                 | je                  0x24
            //   33c0                 | push                edi
            //   40                   | je                  0xe2
            //   5f                   | cmp                 dword ptr [ebp + 0x10], esi
            //   5e                   | je                  0xe2
            //   5b                   | mov                 dword ptr [ebp + 0xc], esi

        $sequence_2 = { eb29 488d0da3460000 e8???????? eb22 488d0d6d460000 e8???????? eb14 }
            // n = 7, score = 100
            //   eb29                 | dec                 esp
            //   488d0da3460000       | arpl                ax, sp
            //   e8????????           |                     
            //   eb22                 | inc                 ecx
            //   488d0d6d460000       | cmp                 esp, -1
            //   e8????????           |                     
            //   eb14                 | je                  0x1a9

        $sequence_3 = { 53 8d45fc 8975fc 50 56 56 }
            // n = 6, score = 100
            //   53                   | test                eax, eax
            //   8d45fc               | jne                 0xfffffd9d
            //   8975fc               | call                edi
            //   50                   | push                eax
            //   56                   | push                esi
            //   56                   | mov                 word ptr [ebp - 0x28], cx

        $sequence_4 = { 57 6a40 ff15???????? 8903 85c0 741c 57 }
            // n = 7, score = 100
            //   57                   | arpl                dx, cx
            //   6a40                 | dec                 eax
            //   ff15????????         |                     
            //   8903                 | add                 esp, 0x30
            //   85c0                 | pop                 edi
            //   741c                 | ret                 
            //   57                   | dec                 eax

        $sequence_5 = { 4883c430 5f c3 ff15???????? 488d0dd9710000 }
            // n = 5, score = 100
            //   4883c430             | pop                 ebp
            //   5f                   | jmp                 0x2b
            //   c3                   | dec                 eax
            //   ff15????????         |                     
            //   488d0dd9710000       | lea                 ecx, [0x46a3]

        $sequence_6 = { ff15???????? 4c63e0 4183fcff 0f849f010000 85c0 }
            // n = 5, score = 100
            //   ff15????????         |                     
            //   4c63e0               | inc                 ebp
            //   4183fcff             | mov                 ecx, esp
            //   0f849f010000         | dec                 eax
            //   85c0                 | mov                 dword ptr [esp + 0x330], edi

        $sequence_7 = { 751a 50 6a18 50 50 }
            // n = 5, score = 100
            //   751a                 | test                eax, eax
            //   50                   | push                edi
            //   6a18                 | push                0x40
            //   50                   | mov                 dword ptr [ebx], eax
            //   50                   | test                eax, eax

        $sequence_8 = { 03d1 81e2ff000080 7d0a ffca 81ca00ffffff ffc2 4863ca }
            // n = 7, score = 100
            //   03d1                 | test                eax, eax
            //   81e2ff000080         | dec                 eax
            //   7d0a                 | mov                 ecx, dword ptr [esp + 0x30]
            //   ffca                 | xor                 eax, eax
            //   81ca00ffffff         | dec                 eax
            //   ffc2                 | add                 esp, 0x138
            //   4863ca               | pop                 ebx

        $sequence_9 = { ff15???????? ff15???????? 8b542468 4c8d8510010000 488d0d53660000 458bcc 4889bc2430030000 }
            // n = 7, score = 100
            //   ff15????????         |                     
            //   ff15????????         |                     
            //   8b542468             | dec                 eax
            //   4c8d8510010000       | lea                 edx, [ebp + 0x3c0]
            //   488d0d53660000       | dec                 eax
            //   458bcc               | lea                 ecx, [0x7196]
            //   4889bc2430030000     | mov                 edx, dword ptr [esp + 0x68]

        $sequence_10 = { 488b4c2450 3d02010000 751b 8b9424f8000000 }
            // n = 4, score = 100
            //   488b4c2450           | dec                 esp
            //   3d02010000           | lea                 eax, [ebp + 0x110]
            //   751b                 | dec                 eax
            //   8b9424f8000000       | lea                 ecx, [0x6653]

        $sequence_11 = { 0f84dc000000 397510 0f84d9000000 89750c 8bce 0fb78108100010 }
            // n = 6, score = 100
            //   0f84dc000000         | lea                 ecx, [0x71d9]
            //   397510               | test                eax, eax
            //   0f84d9000000         | jne                 0x22
            //   89750c               | dec                 eax
            //   8bce                 | lea                 ecx, [0x6b49]
            //   0fb78108100010       | mov                 edx, eax

        $sequence_12 = { 7459 4c8d4da0 4c8d85b0010000 488d95c0030000 488d0d96710000 }
            // n = 5, score = 100
            //   7459                 | je                  0x5b
            //   4c8d4da0             | dec                 esp
            //   4c8d85b0010000       | lea                 ecx, [ebp - 0x60]
            //   488d95c0030000       | dec                 esp
            //   488d0d96710000       | lea                 eax, [ebp + 0x1b0]

        $sequence_13 = { 488b4c2430 ff15???????? 33c0 4881c438010000 5b 5d }
            // n = 6, score = 100
            //   488b4c2430           | dec                 eax
            //   ff15????????         |                     
            //   33c0                 | mov                 ecx, dword ptr [esp + 0x50]
            //   4881c438010000       | cmp                 eax, 0x102
            //   5b                   | jne                 0x22
            //   5d                   | mov                 edx, dword ptr [esp + 0xf8]

        $sequence_14 = { 85c0 0f8597fdffff ffd7 e9???????? }
            // n = 4, score = 100
            //   85c0                 | add                 edx, ecx
            //   0f8597fdffff         | and                 edx, 0x800000ff
            //   ffd7                 | jge                 0xc
            //   e9????????           |                     

        $sequence_15 = { 99 8dbd60ffffff 83e207 895dac }
            // n = 4, score = 100
            //   99                   | mov                 ecx, esi
            //   8dbd60ffffff         | movzx               eax, word ptr [ecx + 0x10001008]
            //   83e207               | push                ebx
            //   895dac               | lea                 eax, [ebp - 4]

    condition:
        7 of them and filesize < 123904
}