Feeds

Linux backdoor squirts code into SSH to keep its badness buried

Fokirtor! It LOOKED like legitimate traffic...

The Power of One eBook: Top reasons to choose HP BladeSystem

Security researchers have discovered a Linux backdoor that uses a covert communication protocol to disguise its presence on compromised systems.

The malware ‪was used in an attack on a large (unnamed) hosting provider ‬back in May. It cleverly attempted to avoid setting off any alarm bells by injecting its own communications into legitimate traffic, specifically SSH chatter. SSH is a protocol commonly used to access shell accounts on Unix-like operating systems, a continuous activity for remote administration of websites.

The unknown cybercrooks or cyberspies behind that attack apparently targeted customer record information such as usernames, emails, and passwords using the subtle and stealthy malware, according to an analysis of the backdoor by security researchers at Symantec.

In addition, the malware made use of the Blowfish encryption algorithm to encrypt uploads of stolen data or other communications with a command-and-control network.

The attackers understood the target environment was generally well-protected. In particular, the attackers needed a means to avoid suspicious network traffic or installed files, which may have triggered a security review. Demonstrating sophistication, the attackers devised their own stealthy Linux backdoor to camouflage itself within the Secure Shell (SSH) and other server processes.

This backdoor allowed an attacker to perform the usual functionality — such as executing remote commands — however, the backdoor did not open a network socket or attempt to connect to a command-and-control server (C&C). Rather, the backdoor code was injected into the SSH process to monitor network traffic and look for the following sequence of characters: colon, exclamation mark, semi-colon, period (“:!;.”).

After seeing this pattern, the back door would parse the rest of the traffic and then extract commands which had been encrypted with Blowfish and Base64 encoded.

Symantec concludes that the mystery malware – which it detects as Fokirtor – is different from any other Linux backdoor that its security researchers have previously analysed.

Malware on Linux systems is mostly a server-side problem and incidents of worms and Trojans run into the hundreds or low thousands – as compared to the tens of millions of Windows pathogens and one million plus Android undesirables.

Even so, Symantec claims that Fokirtor is completely different from any previous strain of Linux malware is noteworthy – not least because it suggests the new tactics pioneered by the malware may crop up in follow-up code. ®

Designing a Defense for Mobile Applications

More from The Register

next story
How long is too long to wait for a security fix?
Synology finally patches OpenSSL bugs in Trevor's NAS
Don't look, Snowden: Security biz chases Tails with zero-day flaws alert
Exodus vows not to sell secrets of whistleblower's favorite OS
Roll out the welcome mat to hackers and crackers
Security chap pens guide to bug bounty programs that won't fail like Yahoo!'s
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
Researcher sat on critical IE bugs for THREE YEARS
VUPEN waited for Pwn2Own cash while IE's sandbox leaked
Four fake Google haxbots hit YOUR WEBSITE every day
Goog the perfect ruse to slip into SEO orfice
Putin: Crack Tor for me and I'll make you a MILLIONAIRE
Russian Interior Ministry offers big pile o' roubles for busting pro-privacy browser
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.