rule win_nautilus_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        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 = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { 7404 33c0 eb2b 4c8b4c2448 4c8bc3 ba01000000 488bce }
            // n = 7, score = 100
            //   7404                 | mov                 esp, edi
            //   33c0                 | not                 eax
            //   eb2b                 | inc                 esp
            //   4c8b4c2448           | xor                 esp, ebx
            //   4c8bc3               | rol                 edi, 7
            //   ba01000000           | or                  eax, edx
            //   488bce               | inc                 esp

        $sequence_1 = { 8b8496d06b0800 440fa3c0 0f826cffffff e9???????? 498d4202 488903 b81c000000 }
            // n = 7, score = 100
            //   8b8496d06b0800       | mov                 eax, 1
            //   440fa3c0             | ret                 
            //   0f826cffffff         | dec                 eax
            //   e9????????           |                     
            //   498d4202             | test                edx, edx
            //   488903               | je                  0x382
            //   b81c000000           | test                byte ptr [edx + 9], 3

        $sequence_2 = { c1c804 3347fc 4433d2 448bc0 8bc8 48c1e810 83e03f }
            // n = 7, score = 100
            //   c1c804               | dec                 eax
            //   3347fc               | sub                 esp, 0x40
            //   4433d2               | dec                 ecx
            //   448bc0               | mov                 ebx, ecx
            //   8bc8                 | dec                 eax
            //   48c1e810             | mov                 dword ptr [eax + 0x10], esi
            //   83e03f               | dec                 eax

        $sequence_3 = { 751a 397b10 7515 44397b5c 736a 397b60 7e65 }
            // n = 7, score = 100
            //   751a                 | inc                 esp
            //   397b10               | sub                 cl, al
            //   7515                 | inc                 esp
            //   44397b5c             | cmp                 eax, ecx
            //   736a                 | inc                 ecx
            //   397b60               | mov                 dword ptr [edx + 0xc], esi
            //   7e65                 | setb                al

        $sequence_4 = { eb07 8bd3 e8???????? 488be8 483bf0 7e04 33c0 }
            // n = 7, score = 100
            //   eb07                 | mov                 dword ptr [ebx + 0x340], esp
            //   8bd3                 | dec                 esp
            //   e8????????           |                     
            //   488be8               | mov                 dword ptr [ebx + 0x358], esp
            //   483bf0               | dec                 esp
            //   7e04                 | mov                 dword ptr [ebx + 0x350], esp
            //   33c0                 | dec                 esp

        $sequence_5 = { 884c06ff 4c8933 4c896318 498b4608 48894310 41803f00 7519 }
            // n = 7, score = 100
            //   884c06ff             | dec                 ecx
            //   4c8933               | mov                 edx, esi
            //   4c896318             | dec                 eax
            //   498b4608             | mov                 ecx, esi
            //   48894310             | dec                 eax
            //   41803f00             | add                 esp, 0x20
            //   7519                 | inc                 ecx

        $sequence_6 = { 7416 488bcb 3d12010000 7407 e8???????? ebd0 e8???????? }
            // n = 7, score = 100
            //   7416                 | dec                 eax
            //   488bcb               | mov                 ecx, ebx
            //   3d12010000           | inc                 esp
            //   7407                 | cmp                 dword ptr [ebx + 8], ebp
            //   e8????????           |                     
            //   ebd0                 | jne                 0x12b1
            //   e8????????           |                     

        $sequence_7 = { e8???????? 81fbef030000 7515 e8???????? 488d15915f0300 488d4860 e8???????? }
            // n = 7, score = 100
            //   e8????????           |                     
            //   81fbef030000         | cmp                 edx, ecx
            //   7515                 | jg                  0x255
            //   e8????????           |                     
            //   488d15915f0300       | dec                 eax
            //   488d4860             | lea                 eax, [edx + 1]
            //   e8????????           |                     

        $sequence_8 = { 743c 81e901010000 742d 83e90f 7421 83e907 7415 }
            // n = 7, score = 100
            //   743c                 | dec                 esp
            //   81e901010000         | mov                 dword ptr [ebp - 0x49], edi
            //   742d                 | inc                 ebp
            //   83e90f               | mov                 edx, edi
            //   7421                 | inc                 esp
            //   83e907               | mov                 dword ptr [ebp - 1], edi
            //   7415                 | inc                 ebp

        $sequence_9 = { 7407 498b06 48894830 49893e 488bcb 4c897730 e8???????? }
            // n = 7, score = 100
            //   7407                 | dec                 ecx
            //   498b06               | arpl                cx, di
            //   48894830             | dec                 eax
            //   49893e               | arpl                si, ax
            //   488bcb               | dec                 ecx
            //   4c897730             | add                 eax, eax
            //   e8????????           |                     

    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_*)) 
}