Feeds

Attack on Apache server exposes firewalls, routers and more

Reverse proxy bug may haunt rival webservers, too

Top 5 reasons to deploy VMware with Tegile

Maintainers of the open-source Apache webserver are warning that their HTTP daemon is vulnerable to exploits that expose internal servers to remote attackers who embed special commands in website addresses.

The weakness in 1.3 and all 2.x versions of the Apache HTTP Server can be exploited only under certain conditions. For one, they must be running in reverse proxy mode, a setting often used to perform load balancing or to separate static content from dynamic content. And even then, internal systems are susceptible to unauthorized access only when certain types of reverse proxy rewrite rules are used.

Nonetheless, the vulnerable reverse proxy configurations are common enough that Apache maintainers issued an advisory on Wednesday recommending users examine their systems to make sure they're not at risk.

"When using the RewriteRule or ProxyPassMatch directives to configure a reverse proxy using a pattern match, it is possible to inadvertently expose internal servers to remote users who send carefully crafted requests," the advisory stated. "The server did not validate that the input to the pattern match was a valid path string, so a pattern could expand to an unintended target URL."

The vulnerability was reported by Context Information Security, an information security consultancy with offices in London, among other cities. In a blog post, researchers with the company said the weakness can be exploited to gain unauthorized access to a highly sensitive DMZ, or "demilitarized zone" resources inside an organization that should be available only to validated users.

"We can access any internal/DMZ system which the proxy can access including administration interfaces on firewalls, routers, web servers, databases etc.," they wrote. "Context has had plenty of success with this attack where credentials are weak on the internal systems allowing for full network compromise e.g. uploading Trojan WAR files on to JBoss servers."

In a press release, Context said the researchers believe other webservers and proxies may be susceptible to similar exploits.

Apache issued a patch for those who compile their own installations of the webserver. It wouldn't be surprising to see Linux distributions release their own security updates in the next few days. Apache's advisory also contains suggestions for writing proxy rules that prevent the attack from working.

Adding a simple forward slash to certain configurations, for example, will go a long way to protecting sensitive systems. The line is "RewriteRule (.*)\.(jpg|gif|png)" could expose internal servers, while the line "RewriteRule /(.*)\.(jpg|gif|png)" (note the extra "/") will ensure they remain protected.

Security researcher Dan Rosenberg echoed the warning that the damage resulting from a poorly configured proxy server could be catastrophic and that the risk could extend well beyond those who use Apache.

"In the worst case, this could result in a remote attacker being able to read sensitive contents from internal web resources," he wrote in an email. "I wouldn't be *too* surprised if reverse proxy mechanisms in other web servers are affected, but the bug is fairly implementation specific, so there's no way to know without testing." ®

Intelligent flash storage arrays

More from The Register

next story
'Regin': The 'New Stuxnet' spook-grade SOFTWARE WEAPON described
'A degree of technical competence rarely seen'
You really need to do some tech support for Aunty Agnes
Free anti-virus software, expires, stops updating and p0wns the world
You stupid BRICK! PCs running Avast AV can't handle Windows fixes
Fix issued, fingers pointed, forums in flames
Privacy bods offer GOV SPY VICTIMS a FREE SPYWARE SNIFFER
Looks for gov malware that evades most antivirus
Patch NOW! Microsoft slings emergency bug fix at Windows admins
Vulnerability promotes lusers to domain overlords ... oops
HACKERS can DELETE SURVEILLANCE DVRS remotely – report
Hikvision devices wide open to hacking, claim securobods
prev story

Whitepapers

Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
10 threats to successful enterprise endpoint backup
10 threats to a successful backup including issues with BYOD, slow backups and ineffective security.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Protecting against web application threats using SSL
SSL encryption can protect server‐to‐server communications, client devices, cloud resources, and other endpoints in order to help prevent the risk of data loss and losing customer trust.