rule win_nautilus_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        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 = "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 = { 834b30ff 488d0551b30600 48894320 488d054eb30600 488b5320 488d4b38 41b83c000000 }
            // n = 7, score = 100
            //   834b30ff             | dec                 eax
            //   488d0551b30600       | mov                 ecx, edi
            //   48894320             | dec                 eax
            //   488d054eb30600       | mov                 ecx, edi
            //   488b5320             | jbe                 0x1691
            //   488d4b38             | cmp                 eax, 1
            //   41b83c000000         | jne                 0x1686

        $sequence_1 = { 7e43 4c8bc0 448bcf 410fb600 3bc2 0f4fd0 3bc1 }
            // n = 7, score = 100
            //   7e43                 | add                 edi, 0x18
            //   4c8bc0               | cmp                 ebx, dword ptr [esi + 0x18]
            //   448bcf               | jl                  0x9e1
            //   410fb600             | dec                 eax
            //   3bc2                 | mov                 ecx, ebp
            //   0f4fd0               | jmp                 0xa4f
            //   3bc1                 | mov                 edi, esi

        $sequence_2 = { ff15???????? 4c897c2438 488bce 3d02010000 488d442478 4889442430 488d442470 }
            // n = 7, score = 100
            //   ff15????????         |                     
            //   4c897c2438           | mov                 esi, eax
            //   488bce               | dec                 eax
            //   3d02010000           | mov                 esi, edx
            //   488d442478           | dec                 eax
            //   4889442430           | mov                 ebx, ecx
            //   488d442470           | dec                 eax

        $sequence_3 = { 817b04ffffff7f 7d0b 488b5c2430 4883c420 5f c3 488d1505480600 }
            // n = 7, score = 100
            //   817b04ffffff7f       | mov                 ecx, edi
            //   7d0b                 | dec                 eax
            //   488b5c2430           | mov                 edx, eax
            //   4883c420             | inc                 esi
            //   5f                   | dec                 eax
            //   c3                   | mov                 ecx, edi
            //   488d1505480600       | setne               cl

        $sequence_4 = { c1e208 48c1e918 4933c8 418b048e 33c2 898388020000 4188ac1980000000 }
            // n = 7, score = 100
            //   c1e208               | dec                 edx
            //   48c1e918             | lea                 ecx, [eax + eax]
            //   4933c8               | dec                 ecx
            //   418b048e             | add                 dword ptr [ebx + 8], ecx
            //   33c2                 | dec                 ecx
            //   898388020000         | cmp                 dword ptr [ebx + 8], ecx
            //   4188ac1980000000     | dec                 eax

        $sequence_5 = { 807c243853 0f85e7000000 488d542438 448bc7 488bcb e8???????? 807c243800 }
            // n = 7, score = 100
            //   807c243853           | mov                 ebx, dword ptr [esp + 0x40]
            //   0f85e7000000         | dec                 eax
            //   488d542438           | mov                 ecx, esi
            //   448bc7               | dec                 esp
            //   488bcb               | mov                 ecx, eax
            //   e8????????           |                     
            //   807c243800           | dec                 eax

        $sequence_6 = { 4c8d159bbdfbff 03f2 4b8b8cead05d0900 428a443108 84c0 0f8937030000 807d6002 }
            // n = 7, score = 100
            //   4c8d159bbdfbff       | dec                 eax
            //   03f2                 | mov                 dword ptr [esp + 8], ebx
            //   4b8b8cead05d0900     | dec                 eax
            //   428a443108           | mov                 dword ptr [esp + 0x10], esi
            //   84c0                 | dec                 eax
            //   0f8937030000         | mov                 dword ptr [esp + 0x18], edi
            //   807d6002             | inc                 ecx

        $sequence_7 = { e8???????? 85c0 7522 8d7b01 488d4df8 8bd7 e8???????? }
            // n = 7, score = 100
            //   e8????????           |                     
            //   85c0                 | dec                 esp
            //   7522                 | mov                 dword ptr [ecx + 0x90], ebx
            //   8d7b01               | dec                 esp
            //   488d4df8             | mov                 dword ptr [ecx + 0x80], ebx
            //   8bd7                 | dec                 eax
            //   e8????????           |                     

        $sequence_8 = { e8???????? 85c0 0f85ac000000 8b7d08 83c714 8bcf e8???????? }
            // n = 7, score = 100
            //   e8????????           |                     
            //   85c0                 | dec                 eax
            //   0f85ac000000         | lea                 ecx, [0x226ad]
            //   8b7d08               | inc                 ecx
            //   83c714               | mov                 eax, 1
            //   8bcf                 | dec                 esp
            //   e8????????           |                     

        $sequence_9 = { e8???????? 3b470c 0f8515ffffff 49893c24 eb0d bb0c000000 488bcf }
            // n = 7, score = 100
            //   e8????????           |                     
            //   3b470c               | dec                 eax
            //   0f8515ffffff         | mov                 eax, dword ptr [ebp - 0x31]
            //   49893c24             | dec                 esp
            //   eb0d                 | cmp                 ebp, eax
            //   bb0c000000           | dec                 ecx
            //   488bcf               | mov                 edx, esi

    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_*)) 
}