rule win_nautilus_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-07-11"
        version = "1"
        description = "Detects win.nautilus."
        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.nautilus"
        malpedia_rule_date = "20230705"
        malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41"
        malpedia_version = "20230715"
        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 = { 8b4b24 8b4320 83c1f8 d3e8 894b24 3c38 0f8581e5ffff }
            // n = 7, score = 100
            //   8b4b24               | dec                 eax
            //   8b4320               | sub                 esp, 0x20
            //   83c1f8               | dec                 eax
            //   d3e8                 | mov                 edi, ecx
            //   894b24               | dec                 eax
            //   3c38                 | mov                 ecx, edx
            //   0f8581e5ffff         | dec                 eax

        $sequence_1 = { 8b8fe8000000 2b8ff0000000 894810 488b87e8000000 488987f0000000 4c39ab10010000 7452 }
            // n = 7, score = 100
            //   8b8fe8000000         | dec                 eax
            //   2b8ff0000000         | mov                 ebp, edx
            //   894810               | dec                 esp
            //   488b87e8000000       | mov                 esi, ecx
            //   488987f0000000       | dec                 eax
            //   4c39ab10010000       | mov                 dword ptr [eax + 0x18], esi
            //   7452                 | dec                 eax

        $sequence_2 = { e8???????? 488d4d88 33d2 8bd8 e8???????? 3bd8 740e }
            // n = 7, score = 100
            //   e8????????           |                     
            //   488d4d88             | inc                 ebp
            //   33d2                 | xor                 eax, eax
            //   8bd8                 | dec                 eax
            //   e8????????           |                     
            //   3bd8                 | mov                 ecx, ebx
            //   740e                 | dec                 eax

        $sequence_3 = { 8b55fc 448b45f0 330b 335304 44334308 448b4df4 488b742448 }
            // n = 7, score = 100
            //   8b55fc               | dec                 eax
            //   448b45f0             | sub                 esp, 0x20
            //   330b                 | dec                 eax
            //   335304               | mov                 esi, ecx
            //   44334308             | dec                 ecx
            //   448b4df4             | mov                 ecx, eax
            //   488b742448           | dec                 ecx

        $sequence_4 = { d3f8 4489742440 85c0 745d 8aca 418bc2 4002d6 }
            // n = 7, score = 100
            //   d3f8                 | dec                 eax
            //   4489742440           | mov                 dword ptr [esp + 0x20], ebx
            //   85c0                 | push                ebp
            //   745d                 | push                esi
            //   8aca                 | dec                 eax
            //   418bc2               | mov                 edi, dword ptr [esp + 0x48]
            //   4002d6               | dec                 eax

        $sequence_5 = { 488b4108 4889442460 4885c0 0f843d020000 33ed 4533f6 396828 }
            // n = 7, score = 100
            //   488b4108             | jne                 0x26
            //   4889442460           | dec                 esp
            //   4885c0               | mov                 eax, esi
            //   0f843d020000         | dec                 eax
            //   33ed                 | mov                 edx, esi
            //   4533f6               | dec                 eax
            //   396828               | mov                 ecx, edi

        $sequence_6 = { 7d16 4863cf 8a841919010000 42888401800a0900 ffc7 ebde 488b0d???????? }
            // n = 7, score = 100
            //   7d16                 | inc                 esp
            //   4863cf               | mov                 byte ptr [edx], bl
            //   8a841919010000       | jmp                 0x1125
            //   42888401800a0900     | inc                 esp
            //   ffc7                 | mov                 byte ptr [edx], cl
            //   ebde                 | dec                 eax
            //   488b0d????????       |                     

        $sequence_7 = { 8b442408 3344240c 4123c3 458bdd 33442408 450bd8 03d0 }
            // n = 7, score = 100
            //   8b442408             | push                esi
            //   3344240c             | push                edi
            //   4123c3               | dec                 eax
            //   458bdd               | sub                 esp, 0x60
            //   33442408             | dec                 eax
            //   450bd8               | mov                 eax, dword ptr [ecx + 0x2a8]
            //   03d0                 | dec                 eax

        $sequence_8 = { 773e 4983c002 4983ea02 3bcb 753a 4d3bc1 7547 }
            // n = 7, score = 100
            //   773e                 | dec                 eax
            //   4983c002             | cmp                 dword ptr [eax], ecx
            //   4983ea02             | jne                 0x1079
            //   3bcb                 | dec                 ecx
            //   753a                 | inc                 ecx
            //   4d3bc1               | dec                 ecx
            //   7547                 | add                 eax, 8

        $sequence_9 = { e8???????? 8bc8 83f917 0f8f1b010000 7455 83f905 0f8431fdffff }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8bc8                 | mov                 ecx, esi
            //   83f917               | dec                 esp
            //   0f8f1b010000         | mov                 eax, eax
            //   7455                 | dec                 eax
            //   83f905               | lea                 ecx, [ebp + 0x1a0]
            //   0f8431fdffff         | dec                 esp

    condition:
        7 of them and filesize < 1302528
}

rule win_nautilus_w0 {
    meta:
        description = "Rule for detection of Nautilus based on assembly code for a modified RC4 loop"
        author = "NCSC UK"
        hash = "a415ab193f6cd832a0de4fcc48d5f53d6f0b06d5e13b3c359878c6c31f3e7ec3"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.nautilus"
        malpedia_version = "20180226"
        malpedia_license = "CC BY-NC-SA 4.0"
        malpedia_sharing = "TLP:WHITE"
    strings:
        $rc4_loop = {42 0F B6 14 04 41 FF C0 03 D7 0F B6 CA 8A 14 0C 43 32 14 13 41 88 12 49 FF C2
        49 FF C9}
        $rc4_key = {31 42 31 34 34 30 44 39 30 46 43 39 42 43 42 34 36 41 39 41 43 39 36 34 33 38
        46 45 45 41 38 42}
        $string_0 = "nautilus-service.dll" ascii
        $string_1 = "oxygen.dll" ascii
        $string_2 = "config_listen.system" ascii
        $string_3 = "ctx.system" ascii
        $string_4 = "3FDA3998-BEF5-426D-82D8-1A71F29ADDC3" ascii
        $string_5 = "C:\\ProgramData\\Microsoft\\Windows\\Caches\\{%s}.2.ver0x0000000000000001.db"
    condition:
        ($rc4_loop and $rc4_key) or (all of ($string_*)) 
}