SYMBOLCOMMON_NAMEaka. SYNONYMS
win.balkan_door (Back to overview)

BalkanDoor


According to ESET, BalkanDoor is a simple backdoor with a small number of commands (download and execute a file, create a remote shell, take a screenshot). It can be used to automate tasks on the compromised computer or to automatically control several affected computers at once. We have seen six versions of the backdoor, with a range of supported commands, evolve since 2016.

References
2019-08-14ESET ResearchZuzana Hromcová
@online{hromcov:20190814:in:4da809c, author = {Zuzana Hromcová}, title = {{In the Balkans, businesses are under fire from a double‑barreled weapon}}, date = {2019-08-14}, organization = {ESET Research}, url = {https://www.welivesecurity.com/2019/08/14/balkans-businesses-double-barreled-weapon/}, language = {English}, urldate = {2019-11-14} } In the Balkans, businesses are under fire from a double‑barreled weapon
BalkanDoor BalkanRAT
Yara Rules
[TLP:WHITE] win_balkan_door_auto (20220516 | Detects win.balkan_door.)
rule win_balkan_door_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        version = "1"
        description = "Detects win.balkan_door."
        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.balkan_door"
        malpedia_rule_date = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { ff15???????? 6a03 6a00 6a00 ff15???????? }
            // n = 5, score = 700
            //   ff15????????         |                     
            //   6a03                 | push                3
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   ff15????????         |                     

        $sequence_1 = { 8be5 5d c3 8d85d0fdffff c785ccfdffff00000000 }
            // n = 5, score = 700
            //   8be5                 | mov                 esp, ebp
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   8d85d0fdffff         | lea                 eax, [ebp - 0x230]
            //   c785ccfdffff00000000     | mov    dword ptr [ebp - 0x234], 0

        $sequence_2 = { 8bf8 85ff 7438 56 683f000f00 68???????? }
            // n = 6, score = 700
            //   8bf8                 | mov                 edi, eax
            //   85ff                 | test                edi, edi
            //   7438                 | je                  0x3a
            //   56                   | push                esi
            //   683f000f00           | push                0xf003f
            //   68????????           |                     

        $sequence_3 = { 8be5 5d c3 8d85d0fdffff }
            // n = 4, score = 700
            //   8be5                 | mov                 esp, ebp
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   8d85d0fdffff         | lea                 eax, [ebp - 0x230]

        $sequence_4 = { 6a02 6a10 6a04 68???????? }
            // n = 4, score = 700
            //   6a02                 | push                2
            //   6a10                 | push                0x10
            //   6a04                 | push                4
            //   68????????           |                     

        $sequence_5 = { 8985ccfdffff 5f 5b 56 }
            // n = 4, score = 700
            //   8985ccfdffff         | mov                 dword ptr [ebp - 0x234], eax
            //   5f                   | pop                 edi
            //   5b                   | pop                 ebx
            //   56                   | push                esi

        $sequence_6 = { 8bf0 85f6 740b 6a00 6a00 56 }
            // n = 6, score = 700
            //   8bf0                 | mov                 esi, eax
            //   85f6                 | test                esi, esi
            //   740b                 | je                  0xd
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   56                   | push                esi

        $sequence_7 = { ff15???????? 8bf8 85ff 7438 56 683f000f00 68???????? }
            // n = 7, score = 700
            //   ff15????????         |                     
            //   8bf8                 | mov                 edi, eax
            //   85ff                 | test                edi, edi
            //   7438                 | je                  0x3a
            //   56                   | push                esi
            //   683f000f00           | push                0xf003f
            //   68????????           |                     

        $sequence_8 = { 56 ffd7 5e 32c0 }
            // n = 4, score = 700
            //   56                   | push                esi
            //   ffd7                 | call                edi
            //   5e                   | pop                 esi
            //   32c0                 | xor                 al, al

        $sequence_9 = { 50 ff15???????? 8bf8 89bd3cefffff }
            // n = 4, score = 700
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8bf8                 | mov                 edi, eax
            //   89bd3cefffff         | mov                 dword ptr [ebp - 0x10c4], edi

    condition:
        7 of them and filesize < 352256
}
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