rule win_chrysalis_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.chrysalis."
        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.chrysalis"
        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 = { 39bd00fdffff 0f8331fcffff e9???????? c645fc08 }
            // n = 4, score = 100
            //   39bd00fdffff         | cmp                 dword ptr [ebp - 0x300], edi
            //   0f8331fcffff         | jae                 0xfffffc37
            //   e9????????           |                     
            //   c645fc08             | mov                 byte ptr [ebp - 4], 8

        $sequence_1 = { 7ce2 8b5de0 8b45f0 0175fc 8b55f4 8b4d08 42 }
            // n = 7, score = 100
            //   7ce2                 | jl                  0xffffffe4
            //   8b5de0               | mov                 ebx, dword ptr [ebp - 0x20]
            //   8b45f0               | mov                 eax, dword ptr [ebp - 0x10]
            //   0175fc               | add                 dword ptr [ebp - 4], esi
            //   8b55f4               | mov                 edx, dword ptr [ebp - 0xc]
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   42                   | inc                 edx

        $sequence_2 = { 0f4385c8fdffff 8d3c10 57 e8???????? 8b8524fdffff 83c40c }
            // n = 6, score = 100
            //   0f4385c8fdffff       | cmovae              eax, dword ptr [ebp - 0x238]
            //   8d3c10               | lea                 edi, [eax + edx]
            //   57                   | push                edi
            //   e8????????           |                     
            //   8b8524fdffff         | mov                 eax, dword ptr [ebp - 0x2dc]
            //   83c40c               | add                 esp, 0xc

        $sequence_3 = { 83f81f 0f8727010000 52 51 e8???????? 83c408 8b5588 }
            // n = 7, score = 100
            //   83f81f               | cmp                 eax, 0x1f
            //   0f8727010000         | ja                  0x12d
            //   52                   | push                edx
            //   51                   | push                ecx
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8b5588               | mov                 edx, dword ptr [ebp - 0x78]

        $sequence_4 = { e8???????? 8b45fc 83c418 c6040700 8b45f0 5f }
            // n = 6, score = 100
            //   e8????????           |                     
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   83c418               | add                 esp, 0x18
            //   c6040700             | mov                 byte ptr [edi + eax], 0
            //   8b45f0               | mov                 eax, dword ptr [ebp - 0x10]
            //   5f                   | pop                 edi

        $sequence_5 = { 85c9 7521 b99339e177 e8???????? 8b0d???????? 85c0 }
            // n = 6, score = 100
            //   85c9                 | test                ecx, ecx
            //   7521                 | jne                 0x23
            //   b99339e177           | mov                 ecx, 0x77e13993
            //   e8????????           |                     
            //   8b0d????????         |                     
            //   85c0                 | test                eax, eax

        $sequence_6 = { 2bc1 83c0fc 83f81f 0f878d050000 52 51 e8???????? }
            // n = 7, score = 100
            //   2bc1                 | sub                 eax, ecx
            //   83c0fc               | add                 eax, -4
            //   83f81f               | cmp                 eax, 0x1f
            //   0f878d050000         | ja                  0x593
            //   52                   | push                edx
            //   51                   | push                ecx
            //   e8????????           |                     

        $sequence_7 = { 33c9 e8???????? 668b0d???????? ba06000000 668985b2f7ffff e8???????? 668b0d???????? }
            // n = 7, score = 100
            //   33c9                 | xor                 ecx, ecx
            //   e8????????           |                     
            //   668b0d????????       |                     
            //   ba06000000           | mov                 edx, 6
            //   668985b2f7ffff       | mov                 word ptr [ebp - 0x84e], ax
            //   e8????????           |                     
            //   668b0d????????       |                     

        $sequence_8 = { 0f8376020000 88840df0feffff 8b0d???????? 85c9 751b b941346ca0 e8???????? }
            // n = 7, score = 100
            //   0f8376020000         | jae                 0x27c
            //   88840df0feffff       | mov                 byte ptr [ebp + ecx - 0x110], al
            //   8b0d????????         |                     
            //   85c9                 | test                ecx, ecx
            //   751b                 | jne                 0x1d
            //   b941346ca0           | mov                 ecx, 0xa06c3441
            //   e8????????           |                     

        $sequence_9 = { 85c0 757e c7471c01000000 8bce 50 8906 894610 }
            // n = 7, score = 100
            //   85c0                 | test                eax, eax
            //   757e                 | jne                 0x80
            //   c7471c01000000       | mov                 dword ptr [edi + 0x1c], 1
            //   8bce                 | mov                 ecx, esi
            //   50                   | push                eax
            //   8906                 | mov                 dword ptr [esi], eax
            //   894610               | mov                 dword ptr [esi + 0x10], eax

    condition:
        7 of them and filesize < 2514944
}