SystemBC is a proxy malware leveraging SOCKS5. Based on screenshots used in ads on a underground marketplace, Proofpoint decided to call it SystemBC.
SystemBC has been observed occasionally, but more pronounced since June 2019. First samples goes back to October 2018.
rule win_systembc_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-07-11" version = "1" description = "Detects win.systembc." 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.systembc" malpedia_rule_date = "20230705" malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41" malpedia_version = "20230715" 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 = { 8b4518 ab b801000000 5e } // n = 4, score = 800 // 8b4518 | mov eax, dword ptr [ebp + 0x18] // ab | stosd dword ptr es:[edi], eax // b801000000 | mov eax, 1 // 5e | pop esi $sequence_1 = { 8955fc 8975f0 8b049a 8945e8 8b02 8945f8 } // n = 6, score = 800 // 8955fc | mov dword ptr [ebp - 4], edx // 8975f0 | mov dword ptr [ebp - 0x10], esi // 8b049a | mov eax, dword ptr [edx + ebx*4] // 8945e8 | mov dword ptr [ebp - 0x18], eax // 8b02 | mov eax, dword ptr [edx] // 8945f8 | mov dword ptr [ebp - 8], eax $sequence_2 = { 64a130000000 8b400c 8b700c 8b5810 8b36 8b7e30 33c9 } // n = 7, score = 800 // 64a130000000 | mov eax, dword ptr fs:[0x30] // 8b400c | mov eax, dword ptr [eax + 0xc] // 8b700c | mov esi, dword ptr [eax + 0xc] // 8b5810 | mov ebx, dword ptr [eax + 0x10] // 8b36 | mov esi, dword ptr [esi] // 8b7e30 | mov edi, dword ptr [esi + 0x30] // 33c9 | xor ecx, ecx $sequence_3 = { e8???????? 68???????? 50 e8???????? ffd0 6a00 } // n = 6, score = 800 // e8???????? | // 68???????? | // 50 | push eax // e8???????? | // ffd0 | call eax // 6a00 | push 0 $sequence_4 = { 02c2 368a8c2800fcffff 36888c2b00fcffff 3688942800fcffff 02ca 368a8c2900fcffff 300e } // n = 7, score = 800 // 02c2 | add al, dl // 368a8c2800fcffff | mov cl, byte ptr ss:[eax + ebp - 0x400] // 36888c2b00fcffff | mov byte ptr ss:[ebx + ebp - 0x400], cl // 3688942800fcffff | mov byte ptr ss:[eax + ebp - 0x400], dl // 02ca | add cl, dl // 368a8c2900fcffff | mov cl, byte ptr ss:[ecx + ebp - 0x400] // 300e | xor byte ptr [esi], cl $sequence_5 = { 50 e8???????? ffd0 8b85f4feffff } // n = 4, score = 800 // 50 | push eax // e8???????? | // ffd0 | call eax // 8b85f4feffff | mov eax, dword ptr [ebp - 0x10c] $sequence_6 = { 895df4 894dec 8955fc 8975f0 } // n = 4, score = 800 // 895df4 | mov dword ptr [ebp - 0xc], ebx // 894dec | mov dword ptr [ebp - 0x14], ecx // 8955fc | mov dword ptr [ebp - 4], edx // 8975f0 | mov dword ptr [ebp - 0x10], esi $sequence_7 = { 46 4f 75cc 33c0 8dbd00fcffff b940000000 fc } // n = 7, score = 800 // 46 | inc esi // 4f | dec edi // 75cc | jne 0xffffffce // 33c0 | xor eax, eax // 8dbd00fcffff | lea edi, [ebp - 0x400] // b940000000 | mov ecx, 0x40 // fc | cld $sequence_8 = { e8???????? ffd0 6a00 6a00 6a00 6a00 } // n = 6, score = 800 // e8???????? | // ffd0 | call eax // 6a00 | push 0 // 6a00 | push 0 // 6a00 | push 0 // 6a00 | push 0 $sequence_9 = { 6aff ff75d8 e8???????? 8d85d8fdffff } // n = 4, score = 800 // 6aff | push -1 // ff75d8 | push dword ptr [ebp - 0x28] // e8???????? | // 8d85d8fdffff | lea eax, [ebp - 0x228] condition: 7 of them and filesize < 57344 }
If your designated proposal does not fit in any other category, feel free to write a free-text in the comment field below.
Please propose all changes regarding references on the Malpedia library page
Your suggestion will be reviewed before being published. Thank you for contributing!
YYYY-MM-DD
YYYY-MM
YYYY