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 = "2023-01-25" 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 = "20230124" malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686" malpedia_version = "20230125" 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 = { 4f 75cc 33c0 8dbd00fcffff } // n = 4, score = 800 // 4f | dec edi // 75cc | jne 0xffffffce // 33c0 | xor eax, eax // 8dbd00fcffff | lea edi, [ebp - 0x400] $sequence_1 = { 8b4c307c 8955ec 894de8 0bc0 0f8495000000 8d0432 } // n = 6, score = 800 // 8b4c307c | mov ecx, dword ptr [eax + esi + 0x7c] // 8955ec | mov dword ptr [ebp - 0x14], edx // 894de8 | mov dword ptr [ebp - 0x18], ecx // 0bc0 | or eax, eax // 0f8495000000 | je 0x9b // 8d0432 | lea eax, [edx + esi] $sequence_2 = { 668b9554f9ffff 6a00 6a00 6a03 6a00 6a00 } // n = 6, score = 800 // 668b9554f9ffff | mov dx, word ptr [ebp - 0x6ac] // 6a00 | push 0 // 6a00 | push 0 // 6a03 | push 3 // 6a00 | push 0 // 6a00 | push 0 $sequence_3 = { 898538f4ffff 8bbd4cf9ffff 8b8d50f9ffff c6043900 33d2 } // n = 5, score = 800 // 898538f4ffff | mov dword ptr [ebp - 0xbc8], eax // 8bbd4cf9ffff | mov edi, dword ptr [ebp - 0x6b4] // 8b8d50f9ffff | mov ecx, dword ptr [ebp - 0x6b0] // c6043900 | mov byte ptr [ecx + edi], 0 // 33d2 | xor edx, edx $sequence_4 = { 50 6aff ff75d8 e8???????? 8d85d8fdffff 50 } // n = 6, score = 800 // 50 | push eax // 6aff | push -1 // ff75d8 | push dword ptr [ebp - 0x28] // e8???????? | // 8d85d8fdffff | lea eax, [ebp - 0x228] // 50 | push eax $sequence_5 = { 50 6805000020 ffb530f4ffff 68???????? e8???????? } // n = 5, score = 800 // 50 | push eax // 6805000020 | push 0x20000005 // ffb530f4ffff | push dword ptr [ebp - 0xbd0] // 68???????? | // e8???????? | $sequence_6 = { eb02 3007 49 837d0cfe 751c } // n = 5, score = 800 // eb02 | jmp 4 // 3007 | xor byte ptr [edi], al // 49 | dec ecx // 837d0cfe | cmp dword ptr [ebp + 0xc], -2 // 751c | jne 0x1e $sequence_7 = { 8b4de8 03d6 03c6 03ca 3bc2 762f 3bc1 } // n = 7, score = 800 // 8b4de8 | mov ecx, dword ptr [ebp - 0x18] // 03d6 | add edx, esi // 03c6 | add eax, esi // 03ca | add ecx, edx // 3bc2 | cmp eax, edx // 762f | jbe 0x31 // 3bc1 | cmp eax, ecx $sequence_8 = { 8d851cf4ffff 50 6800010000 57 ffb530f4ffff } // n = 5, score = 800 // 8d851cf4ffff | lea eax, [ebp - 0xbe4] // 50 | push eax // 6800010000 | push 0x100 // 57 | push edi // ffb530f4ffff | push dword ptr [ebp - 0xbd0] $sequence_9 = { 8945fc c785f4feffff00000000 8d85f4feffff 50 8d45f8 } // n = 5, score = 800 // 8945fc | mov dword ptr [ebp - 4], eax // c785f4feffff00000000 | mov dword ptr [ebp - 0x10c], 0 // 8d85f4feffff | lea eax, [ebp - 0x10c] // 50 | push eax // 8d45f8 | lea eax, [ebp - 8] 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