rule win_privateloader_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.privateloader."
        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.privateloader"
        malpedia_rule_date = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        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 = { 55 8bec 83ec28 894dd8 8b4508 8945e4 8b4de4 }
            // n = 7, score = 600
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   83ec28               | sub                 esp, 0x28
            //   894dd8               | mov                 dword ptr [ebp - 0x28], ecx
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   8945e4               | mov                 dword ptr [ebp - 0x1c], eax
            //   8b4de4               | mov                 ecx, dword ptr [ebp - 0x1c]

        $sequence_1 = { 8b4d10 51 8b55e8 03550c 52 8b4dd8 e8???????? }
            // n = 7, score = 600
            //   8b4d10               | mov                 ecx, dword ptr [ebp + 0x10]
            //   51                   | push                ecx
            //   8b55e8               | mov                 edx, dword ptr [ebp - 0x18]
            //   03550c               | add                 edx, dword ptr [ebp + 0xc]
            //   52                   | push                edx
            //   8b4dd8               | mov                 ecx, dword ptr [ebp - 0x28]
            //   e8????????           |                     

        $sequence_2 = { 83ec1c 894df8 8b45f8 8b4810 894df4 }
            // n = 5, score = 600
            //   83ec1c               | sub                 esp, 0x1c
            //   894df8               | mov                 dword ptr [ebp - 8], ecx
            //   8b45f8               | mov                 eax, dword ptr [ebp - 8]
            //   8b4810               | mov                 ecx, dword ptr [eax + 0x10]
            //   894df4               | mov                 dword ptr [ebp - 0xc], ecx

        $sequence_3 = { 8b45d8 8b4ddc 8b55d0 8b75d4 }
            // n = 4, score = 600
            //   8b45d8               | mov                 eax, dword ptr [ebp - 0x28]
            //   8b4ddc               | mov                 ecx, dword ptr [ebp - 0x24]
            //   8b55d0               | mov                 edx, dword ptr [ebp - 0x30]
            //   8b75d4               | mov                 esi, dword ptr [ebp - 0x2c]

        $sequence_4 = { 8945fc 8b4dfc 894df4 8b55fc 837a1408 7209 }
            // n = 6, score = 600
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   894df4               | mov                 dword ptr [ebp - 0xc], ecx
            //   8b55fc               | mov                 edx, dword ptr [ebp - 4]
            //   837a1408             | cmp                 dword ptr [edx + 0x14], 8
            //   7209                 | jb                  0xb

        $sequence_5 = { 8b02 894510 8b4d08 894dfc 8b55fc 8955e8 8b45fc }
            // n = 7, score = 600
            //   8b02                 | mov                 eax, dword ptr [edx]
            //   894510               | mov                 dword ptr [ebp + 0x10], eax
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   894dfc               | mov                 dword ptr [ebp - 4], ecx
            //   8b55fc               | mov                 edx, dword ptr [ebp - 4]
            //   8955e8               | mov                 dword ptr [ebp - 0x18], edx
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]

        $sequence_6 = { 8b0d???????? 83f100 6a00 6a00 51 }
            // n = 5, score = 600
            //   8b0d????????         |                     
            //   83f100               | xor                 ecx, 0
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   51                   | push                ecx

        $sequence_7 = { 8b4214 2b45f4 394508 7777 8b4df4 }
            // n = 5, score = 600
            //   8b4214               | mov                 eax, dword ptr [edx + 0x14]
            //   2b45f4               | sub                 eax, dword ptr [ebp - 0xc]
            //   394508               | cmp                 dword ptr [ebp + 8], eax
            //   7777                 | ja                  0x79
            //   8b4df4               | mov                 ecx, dword ptr [ebp - 0xc]

        $sequence_8 = { e8???????? 33d2 b93f000000 f7f1 }
            // n = 4, score = 500
            //   e8????????           |                     
            //   33d2                 | xor                 edx, edx
            //   b93f000000           | mov                 ecx, 0x3f
            //   f7f1                 | div                 ecx

        $sequence_9 = { 8bec 81ec68010000 a1???????? 33c5 8945fc 56 57 }
            // n = 7, score = 400
            //   8bec                 | mov                 ebp, esp
            //   81ec68010000         | sub                 esp, 0x168
            //   a1????????           |                     
            //   33c5                 | xor                 eax, ebp
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   56                   | push                esi
            //   57                   | push                edi

        $sequence_10 = { 56 ff15???????? a3???????? 33c0 5e c3 3b0d???????? }
            // n = 7, score = 400
            //   56                   | push                esi
            //   ff15????????         |                     
            //   a3????????           |                     
            //   33c0                 | xor                 eax, eax
            //   5e                   | pop                 esi
            //   c3                   | ret                 
            //   3b0d????????         |                     

        $sequence_11 = { e8???????? 6bc007 33c9 41 6bc903 }
            // n = 5, score = 400
            //   e8????????           |                     
            //   6bc007               | imul                eax, eax, 7
            //   33c9                 | xor                 ecx, ecx
            //   41                   | inc                 ecx
            //   6bc903               | imul                ecx, ecx, 3

        $sequence_12 = { e8???????? 83c610 83c002 83ef08 a907000000 0f853effffff }
            // n = 6, score = 400
            //   e8????????           |                     
            //   83c610               | add                 esi, 0x10
            //   83c002               | add                 eax, 2
            //   83ef08               | sub                 edi, 8
            //   a907000000           | test                eax, 7
            //   0f853effffff         | jne                 0xffffff44

        $sequence_13 = { 8b4590 8b4d94 8b5588 8b758c }
            // n = 4, score = 400
            //   8b4590               | mov                 eax, dword ptr [ebp - 0x70]
            //   8b4d94               | mov                 ecx, dword ptr [ebp - 0x6c]
            //   8b5588               | mov                 edx, dword ptr [ebp - 0x78]
            //   8b758c               | mov                 esi, dword ptr [ebp - 0x74]

        $sequence_14 = { 0bc8 56 57 7529 }
            // n = 4, score = 300
            //   0bc8                 | or                  ecx, eax
            //   56                   | push                esi
            //   57                   | push                edi
            //   7529                 | jne                 0x2b

        $sequence_15 = { 83c201 8955e0 83d600 8975e4 }
            // n = 4, score = 300
            //   83c201               | add                 edx, 1
            //   8955e0               | mov                 dword ptr [ebp - 0x20], edx
            //   83d600               | adc                 esi, 0
            //   8975e4               | mov                 dword ptr [ebp - 0x1c], esi

        $sequence_16 = { 8b45e4 50 51 52 56 }
            // n = 5, score = 300
            //   8b45e4               | mov                 eax, dword ptr [ebp - 0x1c]
            //   50                   | push                eax
            //   51                   | push                ecx
            //   52                   | push                edx
            //   56                   | push                esi

        $sequence_17 = { 6a04 8d4310 50 6a06 }
            // n = 4, score = 300
            //   6a04                 | push                4
            //   8d4310               | lea                 eax, [ebx + 0x10]
            //   50                   | push                eax
            //   6a06                 | push                6

        $sequence_18 = { 660fef4de0 0f294dc0 0f284dd0 50 }
            // n = 4, score = 300
            //   660fef4de0           | pxor                xmm1, xmmword ptr [ebp - 0x20]
            //   0f294dc0             | movaps              xmmword ptr [ebp - 0x40], xmm1
            //   0f284dd0             | movaps              xmm1, xmmword ptr [ebp - 0x30]
            //   50                   | push                eax

        $sequence_19 = { 8b4598 03d0 8b4d9c 13f1 83c201 }
            // n = 5, score = 300
            //   8b4598               | mov                 eax, dword ptr [ebp - 0x68]
            //   03d0                 | add                 edx, eax
            //   8b4d9c               | mov                 ecx, dword ptr [ebp - 0x64]
            //   13f1                 | adc                 esi, ecx
            //   83c201               | add                 edx, 1

    condition:
        7 of them and filesize < 3670016
}

rule win_privateloader_w0 {
  meta:
    author =    "andretavare5"
    org =       "BitSight"
    date =      "2022-06-06"
    md5 =       "8f70a0f45532261cb4df2800b141551d"
    reference = "https://tavares.re/blog/2022/06/06/hunting-privateloader-pay-per-install-service"
    license =   "CC BY-NC-SA 4.0"
    
    malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.privateloader"
    malpedia_version = "20220824"
    malpedia_license = "CC BY-NC-SA 4.0"
    malpedia_sharing = "TLP:WHITE"
  strings:
    $code = { 66 0F EF (4?|8?) } // pxor xmm(1/0) - str chunk decryption
    $str =  "Content-Type: application/x-www-form-urlencoded" wide ascii
    $ua1 = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" wide ascii
    $ua2 = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.63 Safari/537.36" wide ascii
                              
  condition:
    uint16(0) == 0x5A4D and // MZ
    $str and
    any of ($ua*) and
    #code > 100
}