Feeds

Botnet buries commands in image files

Stego backdoor hub

Internet Security Threat Report 2014

Security researchers have identified a botnet that borrows an idea from steganography by burying commands in jpg images.

The DlKhora botnet, which is primarily geared towards downloading other strains of malware, encodes instructions so that the command and control server appears to be serving up image files, SecureWorks reports.

The server sets the HTTP Content-Type header to “image/jpeg” and prefaces the bot commands with a fake 32-byte JPEG header. The bot checks if the header matches and decodes the rest of the response to retrieve its commands. The commands are encoded using a single byte XOR with 0×4.

The botnet makes no attempt to pad files such that they resemble genuine image files, a factor that marks the servers used by DlKhora out for detection. Malware installed by the botnet agent, as identified by SecureWorks to date, largely consists of ad hijacking nuisances.

Hackers need a method for passing instructions to the Trojan of compromised machines that form part of zombie (botnet) networks. IRC channels used to be the preferred venue for command and control channel but recently this has changed with miscreants experimented with different control channels such as Google Groups, Twitter and now "image" servers. ®

Internet Security Threat Report 2014

More from The Register

next story
George Clooney, WikiLeaks' lawyer wife hand out burner phones to wedding guests
Day 4: 'News'-papers STILL rammed with Clooney nuptials
Shellshock: 'Larger scale attack' on its way, warn securo-bods
Not just web servers under threat - though TENS of THOUSANDS have been hit
Apple's new iPhone 6 vulnerable to last year's TouchID fingerprint hack
But unsophisticated thieves need not attempt this trick
PEAK IPV4? Global IPv6 traffic is growing, DDoS dying, says Akamai
First time the cache network has seen drop in use of 32-bit-wide IP addresses
Oracle SHELLSHOCKER - data titan lists unpatchables
Database kingpin lists 32 products that can't be patched (yet) as GNU fixes second vuln
Researchers tell black hats: 'YOU'RE SOOO PREDICTABLE'
Want to register that domain? We're way ahead of you.
Stunned by Shellshock Bash bug? Patch all you can – or be punished
UK data watchdog rolls up its sleeves, polishes truncheon
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.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
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.