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vulnerability CVE-2015-0235

glibc: buffer overflow of gethostbyname, GHOST

Synthesis of the vulnerability

An attacker can for example send an email using a long IPv4 address, to force the messaging server to resolve this address, and to generate a buffer overflow in gethostbyname() of the glibc, in order to trigger a denial of service, and possibly to execute code. Several programs using the gethostbyname() function are vulnerable with a similar attack vector.
Impacted products: Arkoon FAST360, GAiA, CheckPoint IP Appliance, Provider-1, SecurePlatform, CheckPoint Security Gateway, CheckPoint VSX-1, Cisco ASR, Cisco Catalyst, IOS XE Cisco, IOS XR Cisco, Nexus by Cisco, NX-OS, Prime Infrastructure, Cisco CUCM, XenServer, Clearswift Email Gateway, Debian, Unisphere EMC, VNX Operating Environment, VNX Series, Exim, BIG-IP Hardware, TMOS, HPE BSM, HP Operations, Performance Center, Junos Space, MBS, McAfee Email and Web Security, McAfee Email Gateway, McAfee MOVE AntiVirus, McAfee NSP, McAfee NTBA, McAfee NGFW, VirusScan, McAfee Web Gateway, NetIQ Sentinel, openSUSE, Oracle Communications, Palo Alto Firewall PA***, PAN-OS, PHP, HDX, RealPresence Collaboration Server, RealPresence Distributed Media Application, RealPresence Resource Manager, Polycom VBP, RHEL, SIMATIC, Slackware, SUSE Linux Enterprise Desktop, SLES, Synology DSM, Ubuntu, Unix (platform) ~ not comprehensive, WordPress Core.
Severity: 4/4.
Consequences: user access/rights, denial of service on client.
Provenance: internet server.
Confidence: confirmed by the editor (5/5).
Creation date: 27/01/2015.
Revision date: 27/01/2015.
Identifiers: 198850, 199399, c04577814, c04589512, CERTFR-2015-AVI-043, cisco-sa-20150128-ghost, cpujul2015, cpujul2017, cpuoct2016, cpuoct2017, cpuoct2018, CTX200437, CVE-2015-0235, DSA-3142-1, ESA-2015-030, ESA-2015-041, GHOST, HPSBGN03270, HPSBGN03285, JSA10671, K16057, KM01391662, MDVSA-2015:039, openSUSE-SU-2015:0162-1, openSUSE-SU-2015:0184-1, PAN-SA-2015-0002, RHSA-2015:0090-01, RHSA-2015:0092-01, RHSA-2015:0099-01, RHSA-2015:0101-01, RHSA-2015:0126-01, SB10100, sk104443, SOL16057, SSA:2015-028-01, SSA-994726, SUSE-SU-2015:0158-1, USN-2485-1, VIGILANCE-VUL-16060, VU#967332.

Description of the vulnerability

The glibc library provides two functions to obtain the IP address of a server from its DNS name:
  struct hostent *gethostbyname(const char *name);
  struct hostent *gethostbyname2(const char *name, int af);

For example:
  he = gethostbyname("www.example.com");

These functions also accept to directly process an IP address:
  he = gethostbyname("192.168.1.1");

However, a malformed IPv4 address, which is too long such as 192.168.111111.1 (more than 1024 byte long) triggers an overflow in the __nss_hostname_digits_dots() function.

An attacker can therefore for example send an email using a long IPv4 address, to force the messaging server to resolve this address, and to generate a buffer overflow in gethostbyname() of the glibc, in order to trigger a denial of service, and possibly to execute code.

Several programs using the gethostbyname() function are vulnerable (exim, php, pppd, procmail) with a similar attack vector. The following programs are apparently not vulnerable: apache, cups, dovecot, gnupg, isc-dhcp, lighttpd, mariadb/mysql, nfs-utils, nginx, nodejs, openldap, openssh, postfix, proftpd, pure-ftpd, rsyslog, samba, sendmail, squid, sysklogd, syslog-ng, tcp_wrappers, vsftpd, xinetd.
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