rule win_spectre_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.spectre."
        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.spectre"
        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 = { 6a0c 5b 8b4604 2b06 99 f7fb 8bf8 }
            // n = 7, score = 100
            //   6a0c                 | push                0xc
            //   5b                   | pop                 ebx
            //   8b4604               | mov                 eax, dword ptr [esi + 4]
            //   2b06                 | sub                 eax, dword ptr [esi]
            //   99                   | cdq                 
            //   f7fb                 | idiv                ebx
            //   8bf8                 | mov                 edi, eax

        $sequence_1 = { 894804 894808 eb02 33c0 894520 56 8bc8 }
            // n = 7, score = 100
            //   894804               | mov                 dword ptr [eax + 4], ecx
            //   894808               | mov                 dword ptr [eax + 8], ecx
            //   eb02                 | jmp                 4
            //   33c0                 | xor                 eax, eax
            //   894520               | mov                 dword ptr [ebp + 0x20], eax
            //   56                   | push                esi
            //   8bc8                 | mov                 ecx, eax

        $sequence_2 = { 8d8424f4000000 50 57 8d442454 56 50 e8???????? }
            // n = 7, score = 100
            //   8d8424f4000000       | lea                 eax, [esp + 0xf4]
            //   50                   | push                eax
            //   57                   | push                edi
            //   8d442454             | lea                 eax, [esp + 0x54]
            //   56                   | push                esi
            //   50                   | push                eax
            //   e8????????           |                     

        $sequence_3 = { 897df8 885de4 e8???????? 8b4dfc 8bc6 5f 5e }
            // n = 7, score = 100
            //   897df8               | mov                 dword ptr [ebp - 8], edi
            //   885de4               | mov                 byte ptr [ebp - 0x1c], bl
            //   e8????????           |                     
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   8bc6                 | mov                 eax, esi
            //   5f                   | pop                 edi
            //   5e                   | pop                 esi

        $sequence_4 = { eb29 57 8d4dc8 e8???????? 8d45c8 8bce 50 }
            // n = 7, score = 100
            //   eb29                 | jmp                 0x2b
            //   57                   | push                edi
            //   8d4dc8               | lea                 ecx, [ebp - 0x38]
            //   e8????????           |                     
            //   8d45c8               | lea                 eax, [ebp - 0x38]
            //   8bce                 | mov                 ecx, esi
            //   50                   | push                eax

        $sequence_5 = { 80791300 740c 33c0 80340847 40 83f814 72f6 }
            // n = 7, score = 100
            //   80791300             | cmp                 byte ptr [ecx + 0x13], 0
            //   740c                 | je                  0xe
            //   33c0                 | xor                 eax, eax
            //   80340847             | xor                 byte ptr [eax + ecx], 0x47
            //   40                   | inc                 eax
            //   83f814               | cmp                 eax, 0x14
            //   72f6                 | jb                  0xfffffff8

        $sequence_6 = { ffd6 6a12 ffd6 6a14 ffd6 6a11 ffd6 }
            // n = 7, score = 100
            //   ffd6                 | call                esi
            //   6a12                 | push                0x12
            //   ffd6                 | call                esi
            //   6a14                 | push                0x14
            //   ffd6                 | call                esi
            //   6a11                 | push                0x11
            //   ffd6                 | call                esi

        $sequence_7 = { 8d85dcfdffff 50 56 e8???????? 59 59 8d8ddcfdffff }
            // n = 7, score = 100
            //   8d85dcfdffff         | lea                 eax, [ebp - 0x224]
            //   50                   | push                eax
            //   56                   | push                esi
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   59                   | pop                 ecx
            //   8d8ddcfdffff         | lea                 ecx, [ebp - 0x224]

        $sequence_8 = { 50 8d442454 50 e8???????? b9???????? 83c40c 3bc1 }
            // n = 7, score = 100
            //   50                   | push                eax
            //   8d442454             | lea                 eax, [esp + 0x54]
            //   50                   | push                eax
            //   e8????????           |                     
            //   b9????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   3bc1                 | cmp                 eax, ecx

        $sequence_9 = { e8???????? 83c418 83ec18 8d45e4 8bcc 50 895910 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   83c418               | add                 esp, 0x18
            //   83ec18               | sub                 esp, 0x18
            //   8d45e4               | lea                 eax, [ebp - 0x1c]
            //   8bcc                 | mov                 ecx, esp
            //   50                   | push                eax
            //   895910               | mov                 dword ptr [ecx + 0x10], ebx

    condition:
        7 of them and filesize < 990208
}

rule win_spectre_w0 {  
    meta:  
        author = "Yoroi Malware Zlab"  
        description = "Yara Rule for Spectre RAT, versions 2,3,4"  
        last_updated = "2021_10_08"  
        tlp = "white" 
        category = "informational"  

        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.spectre"
        malpedia_version = "20211022"
        malpedia_hash = ""
        malpedia_rule_date = "20211022"
        malpedia_license = "CC BY-NC-SA 4.0"
        malpedia_sharing = "TLP:WHITE"
    strings:  
        $main = {FF 15 ?? ?? ?? ?? FF 15 ?? ?? ?? ?? 3D B7 00 00 00 75 06 57 E8 ?? 7? 00 00 E8 }  
        $c2_send_request = {ff 15 ?? ?? ?? ?? 85 c0 0f 85 ?? ?? ?? ?? 68 ?? ?? ?? ?? 8d 4f 04 c7 07 01 00 00 00 e8 ?? ?? ?? ?? 8b [0-6] 00 10 00 00 83 f8 08 72 ?? 8b 4? [0-2] 8d 04 45 02 00 00 00 89 4?}  

    condition:  
        all of them and uint16(0) == 0x5A4D  
}