SYMBOLCOMMON_NAMEaka. SYNONYMS
win.bravonc (Back to overview)

BravoNC

Actor(s): Lazarus Group


There is no description at this point.

References
2017-05-22SymantecSymantec Security Response
@online{response:20170522:wannacry:f66a95e, author = {Symantec Security Response}, title = {{WannaCry: Ransomware attacks show strong links to Lazarus group}}, date = {2017-05-22}, organization = {Symantec}, url = {https://www.symantec.com/connect/blogs/wannacry-ransomware-attacks-show-strong-links-lazarus-group}, language = {English}, urldate = {2020-01-06} } WannaCry: Ransomware attacks show strong links to Lazarus group
AlphaNC BravoNC Duuzer Sierra(Alfa,Bravo, ...) WannaCryptor
Yara Rules
[TLP:WHITE] win_bravonc_auto (20200817 | autogenerated rule brought to you by yara-signator)
rule win_bravonc_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-08-17"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.4.0"
        tool_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.bravonc"
        malpedia_rule_date = "20200817"
        malpedia_hash = "8c895fd01eccb47a6225bcb1a3ba53cbb98644c5"
        malpedia_version = "20200817"
        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 / approach 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 = { 85c0 59 7403 895d08 8d45f4 50 }
            // n = 6, score = 100
            //   85c0                 | test                eax, eax
            //   59                   | pop                 ecx
            //   7403                 | je                  5
            //   895d08               | mov                 dword ptr [ebp + 8], ebx
            //   8d45f4               | lea                 eax, [ebp - 0xc]
            //   50                   | push                eax

        $sequence_1 = { 837df800 0f8450030000 8b45fc 8b4d08 83651000 ff4df8 }
            // n = 6, score = 100
            //   837df800             | cmp                 dword ptr [ebp - 8], 0
            //   0f8450030000         | je                  0x356
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   83651000             | and                 dword ptr [ebp + 0x10], 0
            //   ff4df8               | dec                 dword ptr [ebp - 8]

        $sequence_2 = { 8b9e10100000 03c7 99 f7fb }
            // n = 4, score = 100
            //   8b9e10100000         | mov                 ebx, dword ptr [esi + 0x1010]
            //   03c7                 | add                 eax, edi
            //   99                   | cdq                 
            //   f7fb                 | idiv                ebx

        $sequence_3 = { e8???????? 59 8b06 397810 7d08 50 }
            // n = 6, score = 100
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   8b06                 | mov                 eax, dword ptr [esi]
            //   397810               | cmp                 dword ptr [eax + 0x10], edi
            //   7d08                 | jge                 0xa
            //   50                   | push                eax

        $sequence_4 = { 83c208 ebe4 8b349d90b24000 8bcb 23751c 2bd3 d36d1c }
            // n = 7, score = 100
            //   83c208               | add                 edx, 8
            //   ebe4                 | jmp                 0xffffffe6
            //   8b349d90b24000       | mov                 esi, dword ptr [ebx*4 + 0x40b290]
            //   8bcb                 | mov                 ecx, ebx
            //   23751c               | and                 esi, dword ptr [ebp + 0x1c]
            //   2bd3                 | sub                 edx, ebx
            //   d36d1c               | shr                 dword ptr [ebp + 0x1c], cl

        $sequence_5 = { 8bca c1f91f c3 55 8bec 83ec18 8b4508 }
            // n = 7, score = 100
            //   8bca                 | mov                 ecx, edx
            //   c1f91f               | sar                 ecx, 0x1f
            //   c3                   | ret                 
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   83ec18               | sub                 esp, 0x18
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]

        $sequence_6 = { 55 8bec 81ec88000000 53 56 8b750c 57 }
            // n = 7, score = 100
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   81ec88000000         | sub                 esp, 0x88
            //   53                   | push                ebx
            //   56                   | push                esi
            //   8b750c               | mov                 esi, dword ptr [ebp + 0xc]
            //   57                   | push                edi

        $sequence_7 = { 59 8945dc 59 8d45e4 50 8d45dc }
            // n = 6, score = 100
            //   59                   | pop                 ecx
            //   8945dc               | mov                 dword ptr [ebp - 0x24], eax
            //   59                   | pop                 ecx
            //   8d45e4               | lea                 eax, [ebp - 0x1c]
            //   50                   | push                eax
            //   8d45dc               | lea                 eax, [ebp - 0x24]

        $sequence_8 = { ff15???????? 8b0d???????? 53 6bc93c 03c1 a3???????? }
            // n = 6, score = 100
            //   ff15????????         |                     
            //   8b0d????????         |                     
            //   53                   | push                ebx
            //   6bc93c               | imul                ecx, ecx, 0x3c
            //   03c1                 | add                 eax, ecx
            //   a3????????           |                     

        $sequence_9 = { 57 685a230000 68???????? e8???????? }
            // n = 4, score = 100
            //   57                   | push                edi
            //   685a230000           | push                0x235a
            //   68????????           |                     
            //   e8????????           |                     

    condition:
        7 of them and filesize < 131072
}
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