rule win_royal_dns_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        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 = "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 = { 7543 8d95b0f7ffff 8d85a1f1ffff e8???????? eb30 }
            // n = 5, score = 100
            //   7543                 | jne                 0x45
            //   8d95b0f7ffff         | lea                 edx, [ebp - 0x850]
            //   8d85a1f1ffff         | lea                 eax, [ebp - 0xe5f]
            //   e8????????           |                     
            //   eb30                 | jmp                 0x32

        $sequence_1 = { e8???????? 83c40c 8bc6 eb15 8d8da1f1ffff }
            // n = 5, score = 100
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   8bc6                 | mov                 eax, esi
            //   eb15                 | jmp                 0x17
            //   8d8da1f1ffff         | lea                 ecx, [ebp - 0xe5f]

        $sequence_2 = { 8a8d8ff1ffff 80e1f5 02c0 0ac1 b908000000 be???????? }
            // n = 6, score = 100
            //   8a8d8ff1ffff         | mov                 cl, byte ptr [ebp - 0xe71]
            //   80e1f5               | and                 cl, 0xf5
            //   02c0                 | add                 al, al
            //   0ac1                 | or                  al, cl
            //   b908000000           | mov                 ecx, 8
            //   be????????           |                     

        $sequence_3 = { 898594fcffff 8d85d9feffff 83c404 8d5001 8a08 40 84c9 }
            // n = 7, score = 100
            //   898594fcffff         | mov                 dword ptr [ebp - 0x36c], eax
            //   8d85d9feffff         | lea                 eax, [ebp - 0x127]
            //   83c404               | add                 esp, 4
            //   8d5001               | lea                 edx, [eax + 1]
            //   8a08                 | mov                 cl, byte ptr [eax]
            //   40                   | inc                 eax
            //   84c9                 | test                cl, cl

        $sequence_4 = { 0fb6730c 83c40c 56 83c30d }
            // n = 4, score = 100
            //   0fb6730c             | movzx               esi, byte ptr [ebx + 0xc]
            //   83c40c               | add                 esp, 0xc
            //   56                   | push                esi
            //   83c30d               | add                 ebx, 0xd

        $sequence_5 = { 51 ffd6 5b b801000000 }
            // n = 4, score = 100
            //   51                   | push                ecx
            //   ffd6                 | call                esi
            //   5b                   | pop                 ebx
            //   b801000000           | mov                 eax, 1

        $sequence_6 = { 5d c3 8d85e0fcffff 50 68???????? }
            // n = 5, score = 100
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   8d85e0fcffff         | lea                 eax, [ebp - 0x320]
            //   50                   | push                eax
            //   68????????           |                     

        $sequence_7 = { 894208 393d???????? 7c11 6860ea0000 }
            // n = 4, score = 100
            //   894208               | mov                 dword ptr [edx + 8], eax
            //   393d????????         |                     
            //   7c11                 | jl                  0x13
            //   6860ea0000           | push                0xea60

        $sequence_8 = { 8d1cbd04000000 53 e8???????? 8bf0 83c404 }
            // n = 5, score = 100
            //   8d1cbd04000000       | lea                 ebx, [edi*4 + 4]
            //   53                   | push                ebx
            //   e8????????           |                     
            //   8bf0                 | mov                 esi, eax
            //   83c404               | add                 esp, 4

        $sequence_9 = { 51 ff15???????? 85c0 0f8597000000 8b85f8f5ffff 8d95f0f5ffff }
            // n = 6, score = 100
            //   51                   | push                ecx
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   0f8597000000         | jne                 0x9d
            //   8b85f8f5ffff         | mov                 eax, dword ptr [ebp - 0xa08]
            //   8d95f0f5ffff         | lea                 edx, [ebp - 0xa10]

    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
}