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
2021-01-04Bleeping ComputerIonut Ilascu
@online{ilascu:20210104:chinas:9677dc6, author = {Ionut Ilascu}, title = {{China's APT hackers move to ransomware attacks}}, date = {2021-01-04}, organization = {Bleeping Computer}, url = {https://www.bleepingcomputer.com/news/security/chinas-apt-hackers-move-to-ransomware-attacks/}, language = {English}, urldate = {2021-01-11} } China's APT hackers move to ransomware attacks
Clambling PlugX
2021-01-04ProferoProfero, SecurityJoes
@techreport{profero:20210104:apt27:a281786, author = {Profero and SecurityJoes}, title = {{APT27 Turns to Ransomware}}, date = {2021-01-04}, institution = {Profero}, url = {https://shared-public-reports.s3-eu-west-1.amazonaws.com/APT27+turns+to+ransomware.pdf}, language = {English}, urldate = {2021-01-10} } APT27 Turns to Ransomware
Clambling
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 (20220808 | Detects win.clambling.)
rule win_clambling_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-08-05"
        version = "1"
        description = "Detects win.clambling."
        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.clambling"
        malpedia_rule_date = "20220805"
        malpedia_hash = "6ec06c64bcfdbeda64eff021c766b4ce34542b71"
        malpedia_version = "20220808"
        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 = { 498943f0 ff15???????? 85c0 7428 83e801 7415 }
            // n = 6, score = 300
            //   498943f0             | mov                 esi, dword ptr [esp + 0x28]
            //   ff15????????         |                     
            //   85c0                 | dec                 eax
            //   7428                 | cmp                 edi, ebx
            //   83e801               | je                  0x4ef
            //   7415                 | dec                 eax

        $sequence_1 = { 418d5101 33c9 ff15???????? 4533c9 4533c0 418d5101 }
            // n = 6, score = 300
            //   418d5101             | lea                 ecx, [esp + 0x32]
            //   33c9                 | inc                 esp
            //   ff15????????         |                     
            //   4533c9               | lea                 eax, [ebp + 0x40]
            //   4533c0               | xor                 edx, edx
            //   418d5101             | mov                 word ptr [esp + 0x30], bp

        $sequence_2 = { 56 57 4154 4881ec60020000 33db 8be9 4c8be2 }
            // n = 7, score = 300
            //   56                   | inc                 sp
            //   57                   | mov                 dword ptr [ebx + eax*2 + 6], edi
            //   4154                 | movzx               eax, word ptr [esp + 0x80]
            //   4881ec60020000       | mov                 word ptr [ebx], si
            //   33db                 | add                 ax, cx
            //   8be9                 | dec                 ecx
            //   4c8be2               | mov                 ecx, esi

        $sequence_3 = { 415c 5f c3 453be7 }
            // n = 4, score = 300
            //   415c                 | dec                 eax
            //   5f                   | mov                 ecx, dword ptr [esp + 0x80]
            //   c3                   | dec                 eax
            //   453be7               | lea                 eax, [esi + 0xc]

        $sequence_4 = { 488d8424b8000000 488d8c24a8000000 41b920020000 4889442450 44896c2448 44896c2440 }
            // n = 6, score = 300
            //   488d8424b8000000     | test                eax, eax
            //   488d8c24a8000000     | jne                 0xb1e
            //   41b920020000         | dec                 eax
            //   4889442450           | lea                 ecx, [0xf53]
            //   44896c2448           | dec                 eax
            //   44896c2440           | lea                 ebx, [0x6dd3]

        $sequence_5 = { ff15???????? 488b742478 8bc3 488b5c2470 4883c460 }
            // n = 5, score = 300
            //   ff15????????         |                     
            //   488b742478           | mov                 edx, dword ptr [esi + 0x58]
            //   8bc3                 | dec                 eax
            //   488b5c2470           | mov                 ecx, dword ptr [esi + 0x50]
            //   4883c460             | dec                 eax

        $sequence_6 = { 4c8d442430 33d2 c744243001000000 c744243c02000000 ff15???????? 85c0 }
            // n = 6, score = 300
            //   4c8d442430           | mov                 edi, 0xf006
            //   33d2                 | dec                 eax
            //   c744243001000000     | mov                 ecx, edi
            //   c744243c02000000     | dec                 eax
            //   ff15????????         |                     
            //   85c0                 | mov                 ebx, eax

        $sequence_7 = { 4803c9 488b0ccf ff15???????? 3bc3 }
            // n = 4, score = 300
            //   4803c9               | dec                 esp
            //   488b0ccf             | mov                 dword ptr [esp + 0x20], esp
            //   ff15????????         |                     
            //   3bc3                 | dec                 eax

        $sequence_8 = { 4883ec60 498363d800 498363e800 498d43e8 498943d0 }
            // n = 5, score = 300
            //   4883ec60             | cmp                 dword ptr [ebx + 0x408c], 6
            //   498363d800           | jne                 0x1117
            //   498363e800           | mov                 dword ptr [ebx + 0x408c], 7
            //   498d43e8             | mov                 edx, 0x2744
            //   498943d0             | dec                 eax

        $sequence_9 = { ff15???????? 3bc7 7507 66893d???????? }
            // n = 4, score = 300
            //   ff15????????         |                     
            //   3bc7                 | mov                 esi, edi
            //   7507                 | mov                 dword ptr [esp + 0x20], 0x40
            //   66893d????????       |                     

    condition:
        7 of them and filesize < 412672
}
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