Risk
4/11/2012
11:00 AM
50%
50%

Malware Writers Pack In Better Encryption

Expert analysis finds the bad guys increasingly use stronger encryption to protect their malware and botnets.

When a new software threat is discovered, reverse engineers dig into the code to find ways to detect the attack, identify the code and its authors, and discover the purpose behind the malware.

Such investigations pit the digital detectives who reverse engineer malicious programs against the developers who created the malware. In the cat-and-mouse game, reverse engineers can easily find copies of the software to crack open and analyze, and attackers respond by throwing up a number of hurdles to slow down analysts' efforts. Chief among the roadblocks are encryption and obfuscation.

In the not-too-distant past, encryption in malware was a sign of an ambitious effort on the part of the program's author. Today, nearly all malware uses some encryption, and perhaps two-thirds of botnets use encrypted communications to obfuscate their activities, says Jeff Edwards, a research analyst with network security firm Arbor Networks.

"There is a gradual trend toward improving their encryption," Edward says. "It all comes down to whether the botnet operators and authors feel pressure to evolve."

With the takedown of the Rustock and Kelihos botnets, which counted tens of thousands of compromised computers among their nodes, the underground operators controlling the botnets are likely feeling pressure to hide their activities to an even greater extent. In addition, as malicious software developers grow more experienced, they frequently add more complex and better implemented encryption to their products.

The Black Energy bot software, for example, originally used a basic encryptor to scramble its executable to avoid detection by antivirus software and used Base64 encoding to scramble its communications. Both were easily reversed engineered. The latest version of Black Energy, however, uses a variant--somewhat flawed, it turns out--of the more robust RC4 stream cipher to encode its communications.

In a recent set of blog posts, Arbor Networks analyzed the encryption of four major bot programs used for denial-of-service. The analyses have found a wide variety of encryption methods, from custom substitution algorithms to the RC4 stream cipher, a popular encryption method used in Secure Sockets Layer, among other protocols. In one analysis, Arbor researched the Dark Comet remote access trojan, which uses RC4 to encrypt its communications and uses other interesting techniques to obfuscate the encryption keys.

"It's all over the map--you get everything from no encryption to really solid encryption," Edward says. "RC4 is the most popular one right now, or some variation of RC4. It's a standard, it's well understood, and it's reasonably secure."

Encryption in botnets has evolved slowly. Five years ago, the Sinowal, or Torpig, trojan used a modified version of the XTEA block cipher to encrypt its configuration data, according to Kurt Baumgartner, senior security researcher with Kaspersky Lab. Since late 2008, the Waledac and Kelihos, or Hlux, botnets used custom implementations of the advanced encryption standard (AES) mixed with other encoding and compression to obfuscate their code and communications, he says.

Read the rest of this article on Dark Reading.

See the future of business technology at Interop Las Vegas, May 6-10. It's the best place to learn how cloud computing, mobile, video, virtualization, and other key technologies work together to drive business. Register today with priority code CPQCNL07 to get a free Expo Pass or to save 25% on Flex and Conference passes..

Comment  | 
Print  | 
More Insights
Register for Dark Reading Newsletters
White Papers
Cartoon
Current Issue
Flash Poll
Video
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2013-7421
Published: 2015-03-02
The Crypto API in the Linux kernel before 3.18.5 allows local users to load arbitrary kernel modules via a bind system call for an AF_ALG socket with a module name in the salg_name field, a different vulnerability than CVE-2014-9644.

CVE-2014-8160
Published: 2015-03-02
net/netfilter/nf_conntrack_proto_generic.c in the Linux kernel before 3.18 generates incorrect conntrack entries during handling of certain iptables rule sets for the SCTP, DCCP, GRE, and UDP-Lite protocols, which allows remote attackers to bypass intended access restrictions via packets with disall...

CVE-2014-9644
Published: 2015-03-02
The Crypto API in the Linux kernel before 3.18.5 allows local users to load arbitrary kernel modules via a bind system call for an AF_ALG socket with a parenthesized module template expression in the salg_name field, as demonstrated by the vfat(aes) expression, a different vulnerability than CVE-201...

CVE-2015-0239
Published: 2015-03-02
The em_sysenter function in arch/x86/kvm/emulate.c in the Linux kernel before 3.18.5, when the guest OS lacks SYSENTER MSR initialization, allows guest OS users to gain guest OS privileges or cause a denial of service (guest OS crash) by triggering use of a 16-bit code segment for emulation of a SYS...

CVE-2014-8921
Published: 2015-03-01
The IBM Notes Traveler Companion application 1.0 and 1.1 before 201411010515 for Window Phone, as distributed in IBM Notes Traveler 9.0.1, does not properly restrict the number of executions of the automatic configuration option, which makes it easier for remote attackers to capture credentials by c...

Dark Reading Radio
Archived Dark Reading Radio
How can security professionals better engage with their peers, both in person and online? In this Dark Reading Radio show, we will talk to leaders at some of the security industry’s professional organizations about how security pros can get more involved – with their colleagues in the same industry, with their peers in other industries, and with the IT security community as a whole.