rule win_blister_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        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 = "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 = { 750b 8b450c 832000 33c0 40 eb02 33c0 }
            // n = 7, score = 100
            //   750b                 | jne                 0xd
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   832000               | and                 dword ptr [eax], 0
            //   33c0                 | xor                 eax, eax
            //   40                   | inc                 eax
            //   eb02                 | jmp                 4
            //   33c0                 | xor                 eax, eax

        $sequence_1 = { 89b5a4f7ffff ff37 ff77fc e8???????? 3bc6 8985a8f7ffff }
            // n = 6, score = 100
            //   89b5a4f7ffff         | mov                 dword ptr [ebp - 0x85c], esi
            //   ff37                 | push                dword ptr [edi]
            //   ff77fc               | push                dword ptr [edi - 4]
            //   e8????????           |                     
            //   3bc6                 | cmp                 eax, esi
            //   8985a8f7ffff         | mov                 dword ptr [ebp - 0x858], eax

        $sequence_2 = { 50 ff75ec ff75f8 ff75f0 ff15???????? 85c0 7507 }
            // n = 7, score = 100
            //   50                   | push                eax
            //   ff75ec               | push                dword ptr [ebp - 0x14]
            //   ff75f8               | push                dword ptr [ebp - 8]
            //   ff75f0               | push                dword ptr [ebp - 0x10]
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   7507                 | jne                 9

        $sequence_3 = { 8b8c3d2cf7ffff 8d85a0f7ffff 50 ffb5a4f7ffff e8???????? 3bc6 8985a8f7ffff }
            // n = 7, score = 100
            //   8b8c3d2cf7ffff       | mov                 ecx, dword ptr [ebp + edi - 0x8d4]
            //   8d85a0f7ffff         | lea                 eax, [ebp - 0x860]
            //   50                   | push                eax
            //   ffb5a4f7ffff         | push                dword ptr [ebp - 0x85c]
            //   e8????????           |                     
            //   3bc6                 | cmp                 eax, esi
            //   8985a8f7ffff         | mov                 dword ptr [ebp - 0x858], eax

        $sequence_4 = { 8b4004 ff34b8 8d45f4 ff75f0 50 e8???????? }
            // n = 6, score = 100
            //   8b4004               | mov                 eax, dword ptr [eax + 4]
            //   ff34b8               | push                dword ptr [eax + edi*4]
            //   8d45f4               | lea                 eax, [ebp - 0xc]
            //   ff75f0               | push                dword ptr [ebp - 0x10]
            //   50                   | push                eax
            //   e8????????           |                     

        $sequence_5 = { 0fb700 ff750c 50 ff15???????? 47 3b7e24 7ce5 }
            // n = 7, score = 100
            //   0fb700               | movzx               eax, word ptr [eax]
            //   ff750c               | push                dword ptr [ebp + 0xc]
            //   50                   | push                eax
            //   ff15????????         |                     
            //   47                   | inc                 edi
            //   3b7e24               | cmp                 edi, dword ptr [esi + 0x24]
            //   7ce5                 | jl                  0xffffffe7

        $sequence_6 = { 8d4dec e8???????? 8d4de4 e8???????? 8d4df4 e8???????? 53 }
            // n = 7, score = 100
            //   8d4dec               | lea                 ecx, [ebp - 0x14]
            //   e8????????           |                     
            //   8d4de4               | lea                 ecx, [ebp - 0x1c]
            //   e8????????           |                     
            //   8d4df4               | lea                 ecx, [ebp - 0xc]
            //   e8????????           |                     
            //   53                   | push                ebx

        $sequence_7 = { 56 b800010000 57 8bf8 eb28 ff750c ff7508 }
            // n = 7, score = 100
            //   56                   | push                esi
            //   b800010000           | mov                 eax, 0x100
            //   57                   | push                edi
            //   8bf8                 | mov                 edi, eax
            //   eb28                 | jmp                 0x2a
            //   ff750c               | push                dword ptr [ebp + 0xc]
            //   ff7508               | push                dword ptr [ebp + 8]

        $sequence_8 = { ab 895dd0 894dd4 894ddc ab 395e0c }
            // n = 6, score = 100
            //   ab                   | stosd               dword ptr es:[edi], eax
            //   895dd0               | mov                 dword ptr [ebp - 0x30], ebx
            //   894dd4               | mov                 dword ptr [ebp - 0x2c], ecx
            //   894ddc               | mov                 dword ptr [ebp - 0x24], ecx
            //   ab                   | stosd               dword ptr es:[edi], eax
            //   395e0c               | cmp                 dword ptr [esi + 0xc], ebx

        $sequence_9 = { 8b00 eb02 33c0 3985a4f7ffff 0f8dcd000000 8d85ccfbffff 50 }
            // n = 7, score = 100
            //   8b00                 | mov                 eax, dword ptr [eax]
            //   eb02                 | jmp                 4
            //   33c0                 | xor                 eax, eax
            //   3985a4f7ffff         | cmp                 dword ptr [ebp - 0x85c], eax
            //   0f8dcd000000         | jge                 0xd3
            //   8d85ccfbffff         | lea                 eax, [ebp - 0x434]
            //   50                   | push                eax

    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
}