rule win_royal_dns_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.royal_dns."
        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.royal_dns"
        malpedia_rule_date = "20260422"
        malpedia_hash = "a182e35da64e6d71cb55f125c4d4225196523f14"
        malpedia_version = "20260504"
        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 = { 8d8dbffdffff e8???????? 8bf0 83c404 85f6 0f8488000000 68ff000000 }
            // n = 7, score = 100
            //   8d8dbffdffff         | lea                 ecx, [ebp - 0x241]
            //   e8????????           |                     
            //   8bf0                 | mov                 esi, eax
            //   83c404               | add                 esp, 4
            //   85f6                 | test                esi, esi
            //   0f8488000000         | je                  0x8e
            //   68ff000000           | push                0xff

        $sequence_1 = { 33ff 33c9 33f6 84db 744c 90 }
            // n = 6, score = 100
            //   33ff                 | xor                 edi, edi
            //   33c9                 | xor                 ecx, ecx
            //   33f6                 | xor                 esi, esi
            //   84db                 | test                bl, bl
            //   744c                 | je                  0x4e
            //   90                   | nop                 

        $sequence_2 = { 83e01f c1f905 8b0c8d80502500 c1e006 8d440104 8020fe ff36 }
            // n = 7, score = 100
            //   83e01f               | and                 eax, 0x1f
            //   c1f905               | sar                 ecx, 5
            //   8b0c8d80502500       | mov                 ecx, dword ptr [ecx*4 + 0x255080]
            //   c1e006               | shl                 eax, 6
            //   8d440104             | lea                 eax, [ecx + eax + 4]
            //   8020fe               | and                 byte ptr [eax], 0xfe
            //   ff36                 | push                dword ptr [esi]

        $sequence_3 = { 0fb6730c 83c40c 56 83c30d 8d85d8fcffff 53 }
            // n = 6, score = 100
            //   0fb6730c             | movzx               esi, byte ptr [ebx + 0xc]
            //   83c40c               | add                 esp, 0xc
            //   56                   | push                esi
            //   83c30d               | add                 ebx, 0xd
            //   8d85d8fcffff         | lea                 eax, [ebp - 0x328]
            //   53                   | push                ebx

        $sequence_4 = { 03049580502500 eb05 b8???????? f6400420 }
            // n = 4, score = 100
            //   03049580502500       | add                 eax, dword ptr [edx*4 + 0x255080]
            //   eb05                 | jmp                 7
            //   b8????????           |                     
            //   f6400420             | test                byte ptr [eax + 4], 0x20

        $sequence_5 = { 83c102 2bc8 8817 7434 }
            // n = 4, score = 100
            //   83c102               | add                 ecx, 2
            //   2bc8                 | sub                 ecx, eax
            //   8817                 | mov                 byte ptr [edi], dl
            //   7434                 | je                  0x36

        $sequence_6 = { 013d???????? 89410c e8???????? 833800 a3???????? bf03000000 7530 }
            // n = 7, score = 100
            //   013d????????         |                     
            //   89410c               | mov                 dword ptr [ecx + 0xc], eax
            //   e8????????           |                     
            //   833800               | cmp                 dword ptr [eax], 0
            //   a3????????           |                     
            //   bf03000000           | mov                 edi, 3
            //   7530                 | jne                 0x32

        $sequence_7 = { ebde 8bc8 83e01f c1f905 8b0c8d80502500 c1e006 0fbe440104 }
            // n = 7, score = 100
            //   ebde                 | jmp                 0xffffffe0
            //   8bc8                 | mov                 ecx, eax
            //   83e01f               | and                 eax, 0x1f
            //   c1f905               | sar                 ecx, 5
            //   8b0c8d80502500       | mov                 ecx, dword ptr [ecx*4 + 0x255080]
            //   c1e006               | shl                 eax, 6
            //   0fbe440104           | movsx               eax, byte ptr [ecx + eax + 4]

        $sequence_8 = { c0f803 2403 02c9 0ac8 8a45e0 241f 884def }
            // n = 7, score = 100
            //   c0f803               | sar                 al, 3
            //   2403                 | and                 al, 3
            //   02c9                 | add                 cl, cl
            //   0ac8                 | or                  cl, al
            //   8a45e0               | mov                 al, byte ptr [ebp - 0x20]
            //   241f                 | and                 al, 0x1f
            //   884def               | mov                 byte ptr [ebp - 0x11], cl

        $sequence_9 = { 8b0c8d80502500 83e01f c1e006 f644080401 74cd }
            // n = 5, score = 100
            //   8b0c8d80502500       | mov                 ecx, dword ptr [ecx*4 + 0x255080]
            //   83e01f               | and                 eax, 0x1f
            //   c1e006               | shl                 eax, 6
            //   f644080401           | test                byte ptr [eax + ecx + 4], 1
            //   74cd                 | je                  0xffffffcf

    condition:
        7 of them and filesize < 204800
}

import "pe"

rule win_royal_dns_w0 {
    meta:
        author = "Florian Roth"
        description = "Detects malware from APT 15 report by NCC Group"
        reference = "https://goo.gl/HZ5XMN"
        date = "2018-03-10"
        hash = "bc937f6e958b339f6925023bc2af375d669084e9551fd3753e501ef26e36b39d"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.royal_dns"
        malpedia_version = "20180312"
        malpedia_license = "CC BY-NC-SA 4.0"
        malpedia_sharing = "TLP:WHITE"
    strings:
        $x1 = "del c:\\windows\\temp\\r.exe /f /q" fullword ascii
        $x2 = "%s\\r.exe" fullword ascii

        $s1 = "rights.dll" fullword ascii
        $s2 = "\"%s\">>\"%s\"\\s.txt" fullword ascii
        $s3 = "Nwsapagent" fullword ascii
        $s4 = "%s\\r.bat" fullword ascii
        $s5 = "%s\\s.txt" fullword ascii
        $s6 = "runexe" fullword ascii
    condition:
        1 of ($x*) or 2 of them
}

rule win_royal_dns_w1 {
    meta:
        author = "David Cannings"
        description = "DLL implant, originally rights.dll and runs as a service"
        hash = "bc937f6e958b339f6925023bc2af375d669084e9551fd3753e501ef26e36b39d"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.royal_dns"
        malpedia_version = "20180312"
        malpedia_license = "CC BY-NC-SA 4.0"
        malpedia_sharing = "TLP:WHITE"
    strings:
        /*
        56                push    esi
        B8 A7 C6 67 4E    mov     eax, 4E67C6A7h
        83 C1 02          add     ecx, 2
        BA 04 00 00 00    mov     edx, 4
        57                push    edi
        90                nop
        */
        // JSHash implementation (Justin Sobel's hash algorithm)
        $opcodes_jshash = { B8 A7 C6 67 4E 83 C1 02 BA 04 00 00 00 57 90 }

        /*
        0F B6 1C 03       movzx   ebx, byte ptr [ebx+eax]
        8B 55 08          mov     edx, [ebp+arg_0]
        30 1C 17          xor     [edi+edx], bl
        47                inc     edi
        3B 7D 0C          cmp     edi, [ebp+arg_4]
        72 A4             jb      short loc_10003F31
        */
        // Encode loop, used to "encrypt" data before DNS request
        $opcodes_encode = { 0F B6 1C 03 8B 55 08 30 1C 17 47 3B 7D 0C }

        /*
        68 88 13 00 00    push    5000 # Also seen 3000, included below
        FF D6             call    esi ; Sleep
        4F                dec     edi
        75 F6             jnz     short loc_10001554
        */
        // Sleep loop
        $opcodes_sleep_loop = { 68 (88|B8) (13|0B) 00 00 FF D6 4F 75 F6 }

        // Generic strings
        $ = "Nwsapagent" fullword
        $ = "\"%s\">>\"%s\"\\s.txt"
        $ = "myWObject" fullword
        $ = "del c:\\windows\\temp\\r.exe /f /q"
        $ = "del c:\\windows\\temp\\r.ini /f /q"

    condition:
        3 of them
}