rule win_systembc_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.systembc."
        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.systembc"
        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 = { b000 ae 75fd 8a57fe 80fa39 }
            // n = 5, score = 1200
            //   b000                 | mov                 al, 0
            //   ae                   | scasb               al, byte ptr es:[edi]
            //   75fd                 | jne                 0xffffffff
            //   8a57fe               | mov                 dl, byte ptr [edi - 2]
            //   80fa39               | cmp                 dl, 0x39

        $sequence_1 = { 742b ff7518 6a00 6a00 ff75fc }
            // n = 5, score = 1100
            //   742b                 | dec                 eax
            //   ff7518               | sub                 esp, 0x20
            //   6a00                 | dec                 eax
            //   6a00                 | lea                 ecx, [ebp - 0x70]
            //   ff75fc               | dec                 eax

        $sequence_2 = { 6a00 8d85fcfbffff 50 8b45f8 8b08 50 }
            // n = 6, score = 1100
            //   6a00                 | mov                 edx, 0
            //   8d85fcfbffff         | stosd               dword ptr es:[edi], eax
            //   50                   | dec                 eax
            //   8b45f8               | mov                 eax, dword ptr [ebp + 0x30]
            //   8b08                 | stosd               dword ptr es:[edi], eax
            //   50                   | dec                 eax

        $sequence_3 = { 6880b55cd6 8b45f8 8b08 8b91a8000000 50 ffd2 }
            // n = 6, score = 1100
            //   6880b55cd6           | mov                 al, 0
            //   8b45f8               | scasb               al, byte ptr es:[edi]
            //   8b08                 | jne                 0xffffffff
            //   8b91a8000000         | mov                 dl, byte ptr [edi - 2]
            //   50                   | cmp                 dl, 0x39
            //   ffd2                 | scasb               al, byte ptr es:[edi]

        $sequence_4 = { c745e801000000 c745ec06000000 8d45dc 50 8d45e0 50 }
            // n = 6, score = 1100
            //   c745e801000000       | dec                 eax
            //   c745ec06000000       | lea                 ecx, [0x23ca]
            //   8d45dc               | dec                 eax
            //   50                   | mov                 edx, 0x32
            //   8d45e0               | dec                 esp
            //   50                   | lea                 eax, [edi + 4]

        $sequence_5 = { 397d08 7757 837d1000 740e 8b5510 8802 8a07 }
            // n = 7, score = 1100
            //   397d08               | mov                 dword ptr [esp + 0x10], edx
            //   7757                 | dec                 esp
            //   837d1000             | mov                 dword ptr [esp + 0x18], eax
            //   740e                 | push                ebp
            //   8b5510               | dec                 eax
            //   8802                 | mov                 ebp, esp
            //   8a07                 | push                ebx

        $sequence_6 = { ab 837d0c00 7403 ff47fc 837d0800 7403 }
            // n = 6, score = 1100
            //   ab                   | add                 esp, 0x20
            //   837d0c00             | dec                 eax
            //   7403                 | sub                 esp, 0x30
            //   ff47fc               | dec                 eax
            //   837d0800             | mov                 ecx, dword ptr [ebp - 0x68]
            //   7403                 | dec                 eax

        $sequence_7 = { 8b4514 ab 8b4518 ab b801000000 }
            // n = 5, score = 1100
            //   8b4514               | dec                 esp
            //   ab                   | mov                 ecx, eax
            //   8b4518               | dec                 eax
            //   ab                   | add                 esp, 0x20
            //   b801000000           | dec                 eax

        $sequence_8 = { ab b801000000 5e 5f }
            // n = 4, score = 1100
            //   ab                   | mov                 edx, 8
            //   b801000000           | dec                 eax
            //   5e                   | add                 esp, 0x20
            //   5f                   | dec                 eax

        $sequence_9 = { e8???????? 4883c420 4883ec20 488d8de0f2ffff 48c7c208000000 e8???????? 4883c420 }
            // n = 7, score = 200
            //   e8????????           |                     
            //   4883c420             | dec                 eax
            //   4883ec20             | add                 esp, 0x30
            //   488d8de0f2ffff       | test                eax, eax
            //   48c7c208000000       | je                  0xffffff94
            //   e8????????           |                     
            //   4883c420             | dec                 eax

        $sequence_10 = { 488d0dca230000 48c7c232000000 4c8d4704 4c8bc8 e8???????? 4883c420 }
            // n = 6, score = 200
            //   488d0dca230000       | add                 esp, 0x20
            //   48c7c232000000       | dec                 eax
            //   4c8d4704             | sub                 esp, 0x20
            //   4c8bc8               | dec                 eax
            //   e8????????           |                     
            //   4883c420             | lea                 ecx, [ebp - 0xd20]

        $sequence_11 = { 4889542410 4c89442418 55 488bec 53 }
            // n = 5, score = 200
            //   4889542410           | dec                 eax
            //   4c89442418           | mov                 edx, 8
            //   55                   | dec                 eax
            //   488bec               | add                 esp, 0x20
            //   53                   | dec                 eax

        $sequence_12 = { 48c7c100000000 48c7c200000000 49c7c000000000 4c8d4f7c }
            // n = 4, score = 200
            //   48c7c100000000       | mov                 dword ptr [esp + 0x18], eax
            //   48c7c200000000       | push                ebp
            //   49c7c000000000       | dec                 eax
            //   4c8d4f7c             | mov                 ebp, esp

        $sequence_13 = { ab 488b4530 ab 48c7c001000000 }
            // n = 4, score = 200
            //   ab                   | add                 esp, 0x20
            //   488b4530             | dec                 eax
            //   ab                   | mov                 dword ptr [esp + 0x10], edx
            //   48c7c001000000       | dec                 esp

        $sequence_14 = { 4883c420 4883ec30 488b4d98 48c7c200000000 }
            // n = 4, score = 200
            //   4883c420             | lea                 eax, [edi + 4]
            //   4883ec30             | dec                 esp
            //   488b4d98             | mov                 ecx, eax
            //   48c7c200000000       | dec                 eax

        $sequence_15 = { 49c7c100000000 488d8530ffffff 4889442420 ff15???????? 4883c430 85c0 7492 }
            // n = 7, score = 200
            //   49c7c100000000       | dec                 ecx
            //   488d8530ffffff       | mov                 ecx, 0
            //   4889442420           | dec                 eax
            //   ff15????????         |                     
            //   4883c430             | lea                 eax, [ebp - 0xd0]
            //   85c0                 | dec                 eax
            //   7492                 | mov                 dword ptr [esp + 0x20], eax

    condition:
        7 of them and filesize < 75776
}