GHOST: glibc: buffer overflow
A serious vulnerability was discovered, and was baptized GHOST in GNU/Linux. It’s present in all Red Hat Enterprise Linux versions, (CentOS etc.), and Debian systems.
Affected versions:
RHEL(Red Hat Enterprise Linux) version 6.x and 7.x
CentOS Linux version 6.x & 7.x
Ubuntu Linux version 10.04, 12.04 LTS
Debian Linux version 7.x
Linux Mint version 13.0
SUSE Linux Enterprise 11 and older (also OpenSuse Linux 11 or older versions).
Arch Linux glibc version <= 2.18-1
It’s strongly recommended update glibc
What services are using this library?
Run this command to discover all complete affected services
# lsof | grep libc | awk ‘{print $1}’ | sort | uniq
How to know if I’m vulnerable?
Copy this content into ghost.c
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#include <netdb.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> #define CANARY "in_the_coal_mine" struct { char buffer[1024]; char canary[sizeof(CANARY)]; } temp = { "buffer", CANARY }; int main(void) { struct hostent resbuf; struct hostent *result; int herrno; int retval; /*** strlen (name) = size_needed - sizeof (*host_addr) - sizeof (*h_addr_ptrs) - 1; ***/ size_t len = sizeof(temp.buffer) - 16*sizeof(unsigned char) - 2*sizeof(char *) - 1; char name[sizeof(temp.buffer)]; memset(name, '0', len); name[len] = '\0'; retval = gethostbyname_r(name, &resbuf, temp.buffer, sizeof(temp.buffer), &result, &herrno); if (strcmp(temp.canary, CANARY) != 0) { puts("vulnerable"); exit(EXIT_SUCCESS); } if (retval == ERANGE) { puts("not vulnerable"); exit(EXIT_SUCCESS); } puts("should not happen"); exit(EXIT_FAILURE); } |
COMPILE
# gcc ghost.c -o ghost
RUN
#./ghost
HOW TO FIX?
# yum update glibc
And reboot the system because many services are using this library
VCP - MCSA - MCTS - RHCSA - RHCE - RHCVA
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