SYMBOLCOMMON_NAMEaka. SYNONYMS
win.gpcode (Back to overview)

GPCode


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References
2011-01-30Steven K
@online{k:20110130:gpcode:53d8cac, author = {Steven K}, title = {{GpCode Ransomware 2010 Simple Analysis}}, date = {2011-01-30}, url = {http://www.xylibox.com/2011/01/gpcode-ransomware-2010-simple-analysis.html}, language = {English}, urldate = {2019-12-24} } GpCode Ransomware 2010 Simple Analysis
GPCode
2007-07-17SymantecElia Florio
@online{florio:20070717:trojangpcodere:f491e6b, author = {Elia Florio}, title = {{Trojan.Gpcoder.E}}, date = {2007-07-17}, organization = {Symantec}, url = {https://www.symantec.com/security_response/writeup.jsp?docid=2007-071711-3132-99&tabid=2}, language = {English}, urldate = {2020-01-10} } Trojan.Gpcoder.E
GPCode
2006-06-26Kaspersky LabsKaspersky
@online{kaspersky:20060626:erpresser:6c57dc7, author = {Kaspersky}, title = {{Erpresser}}, date = {2006-06-26}, organization = {Kaspersky Labs}, url = {https://de.securelist.com/analysis/59479/erpresser/}, language = {German}, urldate = {2020-01-08} } Erpresser
GPCode
Yara Rules
[TLP:WHITE] win_gpcode_auto (20201023 | autogenerated rule brought to you by yara-signator)
rule win_gpcode_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-12-22"
        version = "1"
        description = "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.gpcode"
        malpedia_rule_date = "20201222"
        malpedia_hash = "30354d830a29f0fbd3714d93d94dea941d77a130"
        malpedia_version = "20201023"
        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???????? a1???????? a3???????? 6800001000 68???????? ff35???????? }
            // n = 6, score = 1400
            //   e8????????           |                     
            //   a1????????           |                     
            //   a3????????           |                     
            //   6800001000           | push                0x100000
            //   68????????           |                     
            //   ff35????????         |                     

        $sequence_1 = { e8???????? e8???????? c705????????01000000 c3 55 }
            // n = 5, score = 1400
            //   e8????????           |                     
            //   e8????????           |                     
            //   c705????????01000000     |     
            //   c3                   | ret                 
            //   55                   | push                ebp

        $sequence_2 = { 68???????? e8???????? 91 6a00 }
            // n = 4, score = 1400
            //   68????????           |                     
            //   e8????????           |                     
            //   91                   | xchg                eax, ecx
            //   6a00                 | push                0

        $sequence_3 = { 51 56 8b0d???????? 49 }
            // n = 4, score = 1100
            //   51                   | push                ecx
            //   56                   | push                esi
            //   8b0d????????         |                     
            //   49                   | dec                 ecx

        $sequence_4 = { 6a03 50 50 6a50 ff35???????? ff75fc ff15???????? }
            // n = 7, score = 1100
            //   6a03                 | push                3
            //   50                   | push                eax
            //   50                   | push                eax
            //   6a50                 | push                0x50
            //   ff35????????         |                     
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   ff15????????         |                     

        $sequence_5 = { e8???????? 68???????? e8???????? 33d2 b940000000 }
            // n = 5, score = 1100
            //   e8????????           |                     
            //   68????????           |                     
            //   e8????????           |                     
            //   33d2                 | xor                 edx, edx
            //   b940000000           | mov                 ecx, 0x40

        $sequence_6 = { c70000000000 51 68???????? 8d450c ff30 e8???????? 0fb603 }
            // n = 7, score = 1100
            //   c70000000000         | mov                 dword ptr [eax], 0
            //   51                   | push                ecx
            //   68????????           |                     
            //   8d450c               | lea                 eax, [ebp + 0xc]
            //   ff30                 | push                dword ptr [eax]
            //   e8????????           |                     
            //   0fb603               | movzx               eax, byte ptr [ebx]

        $sequence_7 = { e8???????? 6a02 68???????? 6a00 e8???????? 0bc0 }
            // n = 6, score = 800
            //   e8????????           |                     
            //   6a02                 | push                2
            //   68????????           |                     
            //   6a00                 | push                0
            //   e8????????           |                     
            //   0bc0                 | or                  eax, eax

        $sequence_8 = { 55 8bec 83c4ec 6800050000 }
            // n = 4, score = 800
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   83c4ec               | add                 esp, -0x14
            //   6800050000           | push                0x500

        $sequence_9 = { c780????????5c2a0000 e8???????? 58 c780????????5c2a0000 }
            // n = 4, score = 800
            //   c780????????5c2a0000     |     
            //   e8????????           |                     
            //   58                   | pop                 eax
            //   c780????????5c2a0000     |     

        $sequence_10 = { 68???????? e8???????? 83f8ff 7505 }
            // n = 4, score = 800
            //   68????????           |                     
            //   e8????????           |                     
            //   83f8ff               | cmp                 eax, -1
            //   7505                 | jne                 7

        $sequence_11 = { 69c0fd430300 2b4c2404 05c39e2600 a3???????? }
            // n = 4, score = 100
            //   69c0fd430300         | imul                eax, eax, 0x343fd
            //   2b4c2404             | sub                 ecx, dword ptr [esp + 4]
            //   05c39e2600           | add                 eax, 0x269ec3
            //   a3????????           |                     

        $sequence_12 = { 8944242c ff15???????? 4f 3bfb 8be8 8bf5 895c2410 }
            // n = 7, score = 100
            //   8944242c             | mov                 dword ptr [esp + 0x2c], eax
            //   ff15????????         |                     
            //   4f                   | dec                 edi
            //   3bfb                 | cmp                 edi, ebx
            //   8be8                 | mov                 ebp, eax
            //   8bf5                 | mov                 esi, ebp
            //   895c2410             | mov                 dword ptr [esp + 0x10], ebx

        $sequence_13 = { 8b442404 e8???????? 85c0 7437 53 56 }
            // n = 6, score = 100
            //   8b442404             | mov                 eax, dword ptr [esp + 4]
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   7437                 | je                  0x39
            //   53                   | push                ebx
            //   56                   | push                esi

        $sequence_14 = { 884b01 8bf8 8b45dc 83c303 8a0f 80f912 7532 }
            // n = 7, score = 100
            //   884b01               | mov                 byte ptr [ebx + 1], cl
            //   8bf8                 | mov                 edi, eax
            //   8b45dc               | mov                 eax, dword ptr [ebp - 0x24]
            //   83c303               | add                 ebx, 3
            //   8a0f                 | mov                 cl, byte ptr [edi]
            //   80f912               | cmp                 cl, 0x12
            //   7532                 | jne                 0x34

        $sequence_15 = { 57 e8???????? 83c40c 3b4510 }
            // n = 4, score = 100
            //   57                   | push                edi
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   3b4510               | cmp                 eax, dword ptr [ebp + 0x10]

        $sequence_16 = { 57 8d7001 50 56 e8???????? 8a45dc 8b4df4 }
            // n = 7, score = 100
            //   57                   | push                edi
            //   8d7001               | lea                 esi, [eax + 1]
            //   50                   | push                eax
            //   56                   | push                esi
            //   e8????????           |                     
            //   8a45dc               | mov                 al, byte ptr [ebp - 0x24]
            //   8b4df4               | mov                 ecx, dword ptr [ebp - 0xc]

        $sequence_17 = { 40 39454c 894558 7c42 3b5e28 0f83f00d0000 }
            // n = 6, score = 100
            //   40                   | inc                 eax
            //   39454c               | cmp                 dword ptr [ebp + 0x4c], eax
            //   894558               | mov                 dword ptr [ebp + 0x58], eax
            //   7c42                 | jl                  0x44
            //   3b5e28               | cmp                 ebx, dword ptr [esi + 0x28]
            //   0f83f00d0000         | jae                 0xdf6

        $sequence_18 = { ff4dfc 837df000 7e04 8345fc04 33c9 85c0 }
            // n = 6, score = 100
            //   ff4dfc               | dec                 dword ptr [ebp - 4]
            //   837df000             | cmp                 dword ptr [ebp - 0x10], 0
            //   7e04                 | jle                 6
            //   8345fc04             | add                 dword ptr [ebp - 4], 4
            //   33c9                 | xor                 ecx, ecx
            //   85c0                 | test                eax, eax

    condition:
        7 of them and filesize < 761856
}
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