SYMBOLCOMMON_NAMEaka. SYNONYMS
win.clambling (Back to overview)

Clambling


Clambling was discovered by Trend Micro and TalentJump. It is a custom malware used by an actor they refer to as DRBControl, which targets gambling and betting companies in Southeast Asia. One version of Clambling uses Dropbox as C&C channel to hide its communication.

References
2020-02-18Trend MicroDaniel Lunghi, Cedric Pernet, Kenney Lu, Jamz Yaneza
@techreport{lunghi:20200218:uncovering:d96f725, author = {Daniel Lunghi and Cedric Pernet and Kenney Lu and Jamz Yaneza}, title = {{Uncovering DRBControl}}, date = {2020-02-18}, institution = {Trend Micro}, url = {https://documents.trendmicro.com/assets/white_papers/wp-uncovering-DRBcontrol.pdf}, language = {English}, urldate = {2020-04-01} } Uncovering DRBControl
Clambling
Yara Rules
[TLP:WHITE] win_clambling_auto (20201014 | autogenerated rule brought to you by yara-signator)
rule win_clambling_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-10-14"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.5.0"
        tool_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.clambling"
        malpedia_rule_date = "20201014"
        malpedia_hash = "a7e3bd57eaf12bf3ea29a863c041091ba3af9ac9"
        malpedia_version = "20201014"
        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 = { 33db 85db 740d 488b07 488bcf ff5030 8bc3 }
            // n = 7, score = 300
            //   33db                 | dec                 ebp
            //   85db                 | lea                 ecx, [ebx + 8]
            //   740d                 | dec                 ecx
            //   488b07               | lea                 edx, [ebx - 0x18]
            //   488bcf               | inc                 ecx
            //   ff5030               | mov                 eax, 1
            //   8bc3                 | dec                 ecx

        $sequence_1 = { 48894c2420 33c9 8bd5 ffd0 }
            // n = 4, score = 300
            //   48894c2420           | xor                 eax, eax
            //   33c9                 | xor                 edx, edx
            //   8bd5                 | inc                 esp
            //   ffd0                 | mov                 ecx, esi

        $sequence_2 = { 4c8d8c24c8000000 448d467c 8bd3 488bcf }
            // n = 4, score = 300
            //   4c8d8c24c8000000     | cmp                 ecx, -1
            //   448d467c             | je                  0x3f3
            //   8bd3                 | dec                 eax
            //   488bcf               | mov                 ecx, dword ptr [esi + 0x80]

        $sequence_3 = { 7505 83c8ff eb18 4c8bcb 4c8bc7 ba03000010 488bce }
            // n = 7, score = 300
            //   7505                 | mov                 dword ptr [ebx + 0x1c8], 4
            //   83c8ff               | dec                 ebp
            //   eb18                 | test                esp, esp
            //   4c8bcb               | jne                 0x1ff6
            //   4c8bc7               | mov                 eax, 6
            //   ba03000010           | dec                 eax
            //   488bce               | mov                 ebx, dword ptr [esp + 0x30]

        $sequence_4 = { ff15???????? 488905???????? 483bc6 7504 }
            // n = 4, score = 300
            //   ff15????????         |                     
            //   488905????????       |                     
            //   483bc6               | dec                 esp
            //   7504                 | mov                 esp, edx

        $sequence_5 = { eb0c 211f eb08 ff15???????? 8bd8 488b4c2458 }
            // n = 6, score = 300
            //   eb0c                 | inc                 ecx
            //   211f                 | or                  ecx, 0xffffffff
            //   eb08                 | sub                 ecx, eax
            //   ff15????????         |                     
            //   8bd8                 | je                  0x1fa0
            //   488b4c2458           | cmp                 ecx, 1

        $sequence_6 = { 56 57 4154 4881ec60020000 33db 8be9 4c8be2 }
            // n = 7, score = 300
            //   56                   | mov                 dword ptr [esp + 0x10], ebx
            //   57                   | push                edi
            //   4154                 | dec                 eax
            //   4881ec60020000       | sub                 esp, 0x270
            //   33db                 | dec                 eax
            //   8be9                 | lea                 ecx, [esp + 0x62]
            //   4c8be2               | pop                 edi

        $sequence_7 = { 488d9424e0000000 4533c9 4889442448 488d442470 4533c0 4889442440 48897c2438 }
            // n = 7, score = 300
            //   488d9424e0000000     | mov                 dword ptr [ebp], edi
            //   4533c9               | dec                 ebp
            //   4889442448           | mov                 dword ptr [esp], edi
            //   488d442470           | dec                 eax
            //   4533c0               | or                  ecx, 0xffffffff
            //   4889442440           | xor                 eax, eax
            //   48897c2438           | dec                 eax

        $sequence_8 = { e8???????? 4533c9 4533c0 418d5101 33c9 ff15???????? 4533c9 }
            // n = 7, score = 300
            //   e8????????           |                     
            //   4533c9               | mov                 eax, 0x506
            //   4533c0               | xor                 ebp, ebp
            //   418d5101             | dec                 esp
            //   33c9                 | lea                 ebx, [0x1b54b]
            //   ff15????????         |                     
            //   4533c9               | dec                 eax

        $sequence_9 = { e8???????? 488d8c2440010000 ba04010000 ff15???????? }
            // n = 4, score = 300
            //   e8????????           |                     
            //   488d8c2440010000     | movzx               eax, bx
            //   ba04010000           | dec                 ecx
            //   ff15????????         |                     

    condition:
        7 of them and filesize < 412672
}
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