rule win_dnschanger_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.dnschanger."
        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.dnschanger"
        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 = { 6a00 6a00 56 ff15???????? 85c0 751a ff15???????? }
            // n = 7, score = 100
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   56                   | push                esi
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   751a                 | jne                 0x1c
            //   ff15????????         |                     

        $sequence_1 = { 8b35???????? 50 ffd6 8b5c2418 8bf8 }
            // n = 5, score = 100
            //   8b35????????         |                     
            //   50                   | push                eax
            //   ffd6                 | call                esi
            //   8b5c2418             | mov                 ebx, dword ptr [esp + 0x18]
            //   8bf8                 | mov                 edi, eax

        $sequence_2 = { 68???????? 68???????? 68???????? 68???????? 51 ffd5 }
            // n = 6, score = 100
            //   68????????           |                     
            //   68????????           |                     
            //   68????????           |                     
            //   68????????           |                     
            //   51                   | push                ecx
            //   ffd5                 | call                ebp

        $sequence_3 = { ff15???????? 50 ff15???????? 8d8500ffffff 50 e8???????? 8b35???????? }
            // n = 7, score = 100
            //   ff15????????         |                     
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8d8500ffffff         | lea                 eax, [ebp - 0x100]
            //   50                   | push                eax
            //   e8????????           |                     
            //   8b35????????         |                     

        $sequence_4 = { ab 33c0 8d7de1 885de0 ab ab ab }
            // n = 7, score = 100
            //   ab                   | stosd               dword ptr es:[edi], eax
            //   33c0                 | xor                 eax, eax
            //   8d7de1               | lea                 edi, [ebp - 0x1f]
            //   885de0               | mov                 byte ptr [ebp - 0x20], bl
            //   ab                   | stosd               dword ptr es:[edi], eax
            //   ab                   | stosd               dword ptr es:[edi], eax
            //   ab                   | stosd               dword ptr es:[edi], eax

        $sequence_5 = { 8d4c2414 50 68???????? 68???????? 68???????? }
            // n = 5, score = 100
            //   8d4c2414             | lea                 ecx, [esp + 0x14]
            //   50                   | push                eax
            //   68????????           |                     
            //   68????????           |                     
            //   68????????           |                     

        $sequence_6 = { 8bf8 8d442410 8b8b9c010000 50 57 }
            // n = 5, score = 100
            //   8bf8                 | mov                 edi, eax
            //   8d442410             | lea                 eax, [esp + 0x10]
            //   8b8b9c010000         | mov                 ecx, dword ptr [ebx + 0x19c]
            //   50                   | push                eax
            //   57                   | push                edi

        $sequence_7 = { 57 57 56 57 ff75fc ff15???????? }
            // n = 6, score = 100
            //   57                   | push                edi
            //   57                   | push                edi
            //   56                   | push                esi
            //   57                   | push                edi
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   ff15????????         |                     

        $sequence_8 = { 85ff 740c 57 6a00 ffd5 }
            // n = 5, score = 100
            //   85ff                 | test                edi, edi
            //   740c                 | je                  0xe
            //   57                   | push                edi
            //   6a00                 | push                0
            //   ffd5                 | call                ebp

        $sequence_9 = { 83c41c c3 8a44242c 84c0 742d 6a00 6a00 }
            // n = 7, score = 100
            //   83c41c               | add                 esp, 0x1c
            //   c3                   | ret                 
            //   8a44242c             | mov                 al, byte ptr [esp + 0x2c]
            //   84c0                 | test                al, al
            //   742d                 | je                  0x2f
            //   6a00                 | push                0
            //   6a00                 | push                0

    condition:
        7 of them and filesize < 49152
}