rule win_nautilus_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-10-14"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.5.0"
        tool_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.nautilus"
        malpedia_rule_date = "20201014"
        malpedia_hash = "a7e3bd57eaf12bf3ea29a863c041091ba3af9ac9"
        malpedia_version = "20201014"
        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 = { ebbb 48895c2418 4889742420 57 4883ec60 488b05???????? 4833c4 }
            // n = 7, score = 100
            //   ebbb                 | test                esi, esi
            //   48895c2418           | je                  0x1a7
            //   4889742420           | dec                 esp
            //   57                   | mov                 eax, esi
            //   4883ec60             | dec                 eax
            //   488b05????????       |                     
            //   4833c4               | mov                 edx, ebp

        $sequence_1 = { 75f2 4585d2 7514 453810 750f 498bc1 48f7d8 }
            // n = 7, score = 100
            //   75f2                 | dec                 eax
            //   4585d2               | inc                 ecx
            //   7514                 | dec                 eax
            //   453810               | add                 ecx, ebx
            //   750f                 | dec                 eax
            //   498bc1               | add                 ecx, edi
            //   48f7d8               | dec                 eax

        $sequence_2 = { 895c8450 418bc2 c1c007 33d0 418bc2 c1c806 33d0 }
            // n = 7, score = 100
            //   895c8450             | je                  0x13bc
            //   418bc2               | dec                 eax
            //   c1c007               | cwde                
            //   33d0                 | dec                 eax
            //   418bc2               | lea                 edx, [esp + 0x60]
            //   c1c806               | mov                 dword ptr [edi + 0x60], 2
            //   33d0                 | dec                 eax

        $sequence_3 = { e9???????? 4885d2 488d3d80e80600 4c8bff 4c0f45fa 498bcf e8???????? }
            // n = 7, score = 100
            //   e9????????           |                     
            //   4885d2               | inc                 esp
            //   488d3d80e80600       | mov                 edi, edx
            //   4c8bff               | dec                 ecx
            //   4c0f45fa             | mov                 edx, ecx
            //   498bcf               | dec                 ecx
            //   e8????????           |                     

        $sequence_4 = { c5f928d1 c5f928c1 4c8d0dc82d0400 c5fb101d???????? c5fb100d???????? c5fb59c2 c5f928e0 }
            // n = 7, score = 100
            //   c5f928d1             | cmp                 eax, eax
            //   c5f928c1             | je                  0x394
            //   4c8d0dc82d0400       | vmovd               xmm0, ecx
            //   c5fb101d????????     |                     
            //   c5fb100d????????     |                     
            //   c5fb59c2             | jae                 0x55d
            //   c5f928e0             | dec                 esp

        $sequence_5 = { c3 488d05fd480500 c3 488d0595480500 c3 488d05cd470500 c3 }
            // n = 7, score = 100
            //   c3                   | dec                 esp
            //   488d05fd480500       | mov                 ecx, esi
            //   c3                   | dec                 esp
            //   488d0595480500       | mov                 dword ptr [ebp + 0x50], esi
            //   c3                   | inc                 ebp
            //   488d05cd470500       | xor                 ebp, ebp
            //   c3                   | dec                 esp

        $sequence_6 = { e8???????? 85c0 741d 4c8bc6 488bd7 488bcf e8???????? }
            // n = 7, score = 100
            //   e8????????           |                     
            //   85c0                 | je                  0x1f92
            //   741d                 | dec                 ebp
            //   4c8bc6               | mov                 dword ptr [edi + 0x10], esp
            //   488bd7               | dec                 esp
            //   488bcf               | mov                 esp, dword ptr [ebp + 0xc8]
            //   e8????????           |                     

        $sequence_7 = { 85db 7e49 488b4740 488934d0 48ffc2 483bd3 7cf0 }
            // n = 7, score = 100
            //   85db                 | dec                 eax
            //   7e49                 | lea                 ecx, [ebp + 0x30]
            //   488b4740             | dec                 esp
            //   488934d0             | mov                 eax, edi
            //   48ffc2               | mov                 edx, 4
            //   483bd3               | mov                 dword ptr [ebp + 0x30], eax
            //   7cf0                 | mov                 eax, dword ptr [ebx + 0x2c]

        $sequence_8 = { ff05???????? 488d4c2420 e8???????? 8bc3 eb05 b800b3ffff 4c8d5c2440 }
            // n = 7, score = 100
            //   ff05????????         |                     
            //   488d4c2420           | dec                 ebp
            //   e8????????           |                     
            //   8bc3                 | mov                 ebx, edx
            //   eb05                 | dec                 esp
            //   b800b3ffff           | lea                 eax, [ebp + 2]
            //   4c8d5c2440           | inc                 ecx

        $sequence_9 = { e8???????? e9???????? 399f54020000 0f84c4030000 488b9fb8020000 488bce 488b03 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   e9????????           |                     
            //   399f54020000         | dec                 eax
            //   0f84c4030000         | lea                 edx, [esp + 0x48]
            //   488b9fb8020000       | dec                 ecx
            //   488bce               | mov                 ecx, esi
            //   488b03               | 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_*)) 
}