rule win_blister_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.blister."
        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.blister"
        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 = { e8???????? 83c608 8b06 85c0 75e7 8b07 8d8d98f5ffff }
            // n = 7, score = 100
            //   e8????????           |                     
            //   83c608               | add                 esi, 8
            //   8b06                 | mov                 eax, dword ptr [esi]
            //   85c0                 | test                eax, eax
            //   75e7                 | jne                 0xffffffe9
            //   8b07                 | mov                 eax, dword ptr [edi]
            //   8d8d98f5ffff         | lea                 ecx, [ebp - 0xa68]

        $sequence_1 = { 8d85f6fdffff 50 e8???????? 832600 83c40c 57 e8???????? }
            // n = 7, score = 100
            //   8d85f6fdffff         | lea                 eax, [ebp - 0x20a]
            //   50                   | push                eax
            //   e8????????           |                     
            //   832600               | and                 dword ptr [esi], 0
            //   83c40c               | add                 esp, 0xc
            //   57                   | push                edi
            //   e8????????           |                     

        $sequence_2 = { 7419 ff7104 ff15???????? 8906 }
            // n = 4, score = 100
            //   7419                 | je                  0x1b
            //   ff7104               | push                dword ptr [ecx + 4]
            //   ff15????????         |                     
            //   8906                 | mov                 dword ptr [esi], eax

        $sequence_3 = { 57 50 89bdf0fbffff 898decfbffff 89bde8fbffff 89bdf8fbffff ff15???????? }
            // n = 7, score = 100
            //   57                   | push                edi
            //   50                   | push                eax
            //   89bdf0fbffff         | mov                 dword ptr [ebp - 0x410], edi
            //   898decfbffff         | mov                 dword ptr [ebp - 0x414], ecx
            //   89bde8fbffff         | mov                 dword ptr [ebp - 0x418], edi
            //   89bdf8fbffff         | mov                 dword ptr [ebp - 0x408], edi
            //   ff15????????         |                     

        $sequence_4 = { 85c0 741c 8b8c3d2cf7ffff ff85a4f7ffff e8???????? 3985a4f7ffff 7ca5 }
            // n = 7, score = 100
            //   85c0                 | test                eax, eax
            //   741c                 | je                  0x1e
            //   8b8c3d2cf7ffff       | mov                 ecx, dword ptr [ebp + edi - 0x8d4]
            //   ff85a4f7ffff         | inc                 dword ptr [ebp - 0x85c]
            //   e8????????           |                     
            //   3985a4f7ffff         | cmp                 dword ptr [ebp - 0x85c], eax
            //   7ca5                 | jl                  0xffffffa7

        $sequence_5 = { e8???????? a1???????? 85c0 7403 5d ffe0 83c8ff }
            // n = 7, score = 100
            //   e8????????           |                     
            //   a1????????           |                     
            //   85c0                 | test                eax, eax
            //   7403                 | je                  5
            //   5d                   | pop                 ebp
            //   ffe0                 | jmp                 eax
            //   83c8ff               | or                  eax, 0xffffffff

        $sequence_6 = { e8???????? 8b4b0c 8d85acf7ffff 50 ffb59cf7ffff e8???????? ffb59cf7ffff }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8b4b0c               | mov                 ecx, dword ptr [ebx + 0xc]
            //   8d85acf7ffff         | lea                 eax, [ebp - 0x854]
            //   50                   | push                eax
            //   ffb59cf7ffff         | push                dword ptr [ebp - 0x864]
            //   e8????????           |                     
            //   ffb59cf7ffff         | push                dword ptr [ebp - 0x864]

        $sequence_7 = { 894d0c 85c9 750d ff7510 50 e8???????? 85c0 }
            // n = 7, score = 100
            //   894d0c               | mov                 dword ptr [ebp + 0xc], ecx
            //   85c9                 | test                ecx, ecx
            //   750d                 | jne                 0xf
            //   ff7510               | push                dword ptr [ebp + 0x10]
            //   50                   | push                eax
            //   e8????????           |                     
            //   85c0                 | test                eax, eax

        $sequence_8 = { 894608 8b4604 85c0 740d 6a00 }
            // n = 5, score = 100
            //   894608               | mov                 dword ptr [esi + 8], eax
            //   8b4604               | mov                 eax, dword ptr [esi + 4]
            //   85c0                 | test                eax, eax
            //   740d                 | je                  0xf
            //   6a00                 | push                0

        $sequence_9 = { e8???????? 8d4dec e8???????? 8d4df4 e8???????? 8b4dfc 8b45e4 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8d4dec               | lea                 ecx, [ebp - 0x14]
            //   e8????????           |                     
            //   8d4df4               | lea                 ecx, [ebp - 0xc]
            //   e8????????           |                     
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   8b45e4               | mov                 eax, dword ptr [ebp - 0x1c]

    condition:
        7 of them and filesize < 1822720
}

rule win_blister_w0 {
    meta:
        author = "Elastic Security"
        description = "Detects Blister loader."
        creation_date = "2021-12-20"
        last_modified = "2021-12-20"
        os = "Windows"
        category_type = "Trojan"
        family = "Blister"
        threat_name = "Windows.Trojan.Blister"
        reference_sample = "0a7778cf6f9a1bd894e89f282f2e40f9d6c9cd4b72be97328e681fe32a1b1a00"
        source = "https://www.elastic.co/de/blog/elastic-security-uncovers-blister-malware-campaign"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.blister"
        malpedia_rule_date = "20211223"
        malpedia_hash = ""
        malpedia_version = "20211223"
        malpedia_sharing = "TLP:WHITE"

    strings:
        $a1 = {8D 45 DC 89 5D EC 50 6A 04 8D 45 F0 50 8D 45 EC 50 6A FF FF D7}
        $a2 = {75 F7 39 4D FC 0F 85 F3 00 00 00 64 A1 30 00 00 00 53 57 89 75}           
condition:
        any of them
}