rule win_nautilus_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-12-22"
        version = "1"
        description = "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 = "20201222"
        malpedia_hash = "30354d830a29f0fbd3714d93d94dea941d77a130"
        malpedia_version = "20201023"
        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 = { e9???????? 4883c302 493bde 0f8420020000 498bf6 482bf3 0fb603 }
            // n = 7, score = 100
            //   e9????????           |                     
            //   4883c302             | je                  0x8ad
            //   493bde               | dec                 esp
            //   0f8420020000         | mov                 esi, dword ptr [esp + 0x68]
            //   498bf6               | dec                 ecx
            //   482bf3               | mov                 edi, eax
            //   0fb603               | dec                 esp

        $sequence_1 = { ffc0 83f832 0f8538080000 4963d3 410fb70c54 8bc1 4803c0 }
            // n = 7, score = 100
            //   ffc0                 | jmp                 0x1139
            //   83f832               | dec                 ecx
            //   0f8538080000         | mov                 ecx, esp
            //   4963d3               | dec                 esp
            //   410fb70c54           | lea                 eax, [esp + 0x30]
            //   8bc1                 | dec                 esp
            //   4803c0               | mov                 esp, esi

        $sequence_2 = { 8bd6 488bcb 448bc0 e8???????? 4863f8 83fe03 7421 }
            // n = 7, score = 100
            //   8bd6                 | dec                 eax
            //   488bcb               | mov                 edx, edi
            //   448bc0               | dec                 eax
            //   e8????????           |                     
            //   4863f8               | mov                 ebp, ecx
            //   83fe03               | dec                 eax
            //   7421                 | lea                 ecx, [eax - 0x68]

        $sequence_3 = { 894308 8b4308 3dff000000 7e6e 488bd3 488bcf e8???????? }
            // n = 7, score = 100
            //   894308               | dec                 eax
            //   8b4308               | lea                 edx, [esp + 0x40]
            //   3dff000000           | inc                 ecx
            //   7e6e                 | mov                 eax, 0x400
            //   488bd3               | test                eax, eax
            //   488bcf               | dec                 eax
            //   e8????????           |                     

        $sequence_4 = { 488bd0 e8???????? 488bc8 4885c0 7509 c7432807000000 eb69 }
            // n = 7, score = 100
            //   488bd0               | dec                 eax
            //   e8????????           |                     
            //   488bc8               | add                 ecx, esi
            //   4885c0               | test                al, al
            //   7509                 | inc                 ecx
            //   c7432807000000       | mov                 dword ptr [eax + 4], esi
            //   eb69                 | setb                al

        $sequence_5 = { e8???????? 488b4f08 4c8d05ce680500 488d151bdb0500 458bcf e8???????? 488b4f08 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   488b4f08             | dec                 eax
            //   4c8d05ce680500       | mov                 dword ptr [edx + 8], eax
            //   488d151bdb0500       | jmp                 0x58f
            //   458bcf               | dec                 eax
            //   e8????????           |                     
            //   488b4f08             | mov                 ecx, dword ptr [ecx + 0x40]

        $sequence_6 = { f20f1116 f20f115630 c7463803000000 e9???????? c1ef17 85ff 740d }
            // n = 7, score = 100
            //   f20f1116             | inc                 ecx
            //   f20f115630           | mov                 dword ptr [esp], ebx
            //   c7463803000000       | inc                 ecx
            //   e9????????           |                     
            //   c1ef17               | mov                 esi, ecx
            //   85ff                 | dec                 esp
            //   740d                 | mov                 esp, dword ptr [ebp + 0x100]

        $sequence_7 = { 744c 488b8580000000 4885c0 7403 832000 4d8bc6 488bd3 }
            // n = 7, score = 100
            //   744c                 | dec                 eax
            //   488b8580000000       | mov                 dword ptr [esp + 0x18], esi
            //   4885c0               | push                edi
            //   7403                 | dec                 eax
            //   832000               | sub                 esp, 0x20
            //   4d8bc6               | dec                 eax
            //   488bd3               | mov                 esi, ecx

        $sequence_8 = { 83ff20 7c10 488b4920 488d155fc20100 e8???????? 488d4703 4c8bcf }
            // n = 7, score = 100
            //   83ff20               | cmp                 eax, 1
            //   7c10                 | jl                  0x2e7
            //   488b4920             | dec                 eax
            //   488d155fc20100       | mov                 eax, edx
            //   e8????????           |                     
            //   488d4703             | dec                 eax
            //   4c8bcf               | add                 esp, 0x28

        $sequence_9 = { 85c0 7421 4c8d4708 488d55cf 488d4dcf e8???????? 8bd8 }
            // n = 7, score = 100
            //   85c0                 | mov                 dword ptr [esp + 0x20], esi
            //   7421                 | dec                 eax
            //   4c8d4708             | mov                 ecx, dword ptr [esp + 0x48]
            //   488d55cf             | inc                 esp
            //   488d4dcf             | mov                 edi, eax
            //   e8????????           |                     
            //   8bd8                 | dec                 eax

    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_*)) 
}