Feeds

*Nix security pandemic – major zlib/libz vuln

It's inside the walls, under the rug, in the ventilator shafts...

  • alert
  • submit to reddit

Internet Security Threat Report 2014

A flaw in the zlib/libz data compression/decompression libraries could enable an attacker to mount a denial of service attack against any Linux or AIX firewall, database server, mail or Web server. It's also possible that arbitrary code could be run on a remote machine.

Because these shared libraries are used by hundreds of packages on numerous platforms, the bug is on a par with the DHCP, SNMP and Sun vulnerabilities recently reported.

The problem here is a stuff-up in a decompression routine which can corrupt the internal data structures of malloc by a double call to the free() function (double-free), discovered by Matthias Clasen. This enables memory space to be cleared twice, and can crash virtually any program.

At the moment there are no known exploits circulating, but of course it's only a matter of time before there will be.

There is no workaround, but most if not all vendors have fixes. Unfortunately, this will apply only to the library on a given system. Apps that link to it dynamically will of course be safe to run after patching, but there are hundreds of apps and services which link statically to or contain implementations of the old code, and these will of course have to be fixed individually.

The Linux kernel also uses the compression library, in the ppp layer and the freeswan IPSec kernel module.

Other apps/services which contain the old code include:

gcc 3.0
gpg
rsync
cvs
rrdtool
freeamp
Netscape (fix in the works)
ssh
vnc
XFree86

A number of these packages (except Netscape) will have been rebuilt either to link dynamically or with their own code updated, but this varies from vendor to vendor. Check with your vendor for the appropriate patches. Once they're installed, it will be necessary to recompile your kernel (if you have the relevant update package) or update the relevant modules. Any apps you built using the old code will have to be recompiled. Generally speaking, you should substitute apps which link dynamically to zlib/libz for ones that link statically or are based on the old code.

Be sure to test all patches thoroughly before integrating them into critical systems.

The repaired zlib version 1.1.4 can be downloaded from zlib.org. CERT has a bulletin with a list of currently-known vulnerable systems, but the list of unknowns is still quite large. However, CERT has proven to be fastidious about updating their advisories as new information becomes available, so do check back regularly.

We'll update this item as soon as we get better information. Data is a bit sketchy at the moment, and we've found some contradictory details in the various vendors' bulletins. ®

Internet Security Threat Report 2014

More from The Register

next story
Docker's app containers are coming to Windows Server, says Microsoft
MS chases app deployment speeds already enjoyed by Linux devs
IBM storage revenues sink: 'We are disappointed,' says CEO
Time to put the storage biz up for sale?
'Hmm, why CAN'T I run a water pipe through that rack of media servers?'
Leaving Las Vegas for Armenia kludging and Dubai dune bashing
Facebook slurps 'paste sites' for STOLEN passwords, sprinkles on hash and salt
Zuck's ad empire DOESN'T see details in plain text. Phew!
Windows 10: Forget Cloudobile, put Security and Privacy First
But - dammit - It would be insane to say 'don't collect, because NSA'
Symantec backs out of Backup Exec: Plans to can appliance in Jan
Will still provide support to existing customers
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.