Polymorphic threats cause pain for traditional anti-virus: Symantec

Criminals employ "much more aggressive strategy"
  • Stilgherrian (CSO Online (Australia))
  • — 09 August, 2011 13:04

The volume of email containing polymorphic malware -- malicious software that can change its characteristics to evade detection by anti-virus defences -- has increased dramatically, according to security vendor Symantec.

Overall the amount of malicious email is relatively stable at one in every 281 emails. However 23.7 percent of malicious emails now contain polymorphic malware, double the figure six months ago, according to the Symantec Intelligence Report: July 2011 (PDF).

Over the same time, the number of variants, or different strains, of malware involved in each attack has grown 25 times.

This indicates a "much more aggressive strategy" on the part of the criminals responsible, according to Symantec's senior intelligence analyst Paul Wood. "Perhaps greater use of automation has enabled them to increase their output to this extent."

Wood believes this "alarming" proliferation almost certainly heightens the risk for many organisations.

"This new breed of malware is likely to be causing a great deal of pain for a great number of traditional anti-virus companies that rely on signatures, heuristics and software emulation in order to detect malicious activity," Wood wrote.

The most recent malware samples detected by Symantec were specifically designed to evade the software emulation used by some anti-virus software to analyse the code of potential malware.

"This new breed of malware includes a series of unnecessary 'jump' instructions in the startup code, which are introduced in between the real instructions specifically to confound the anti-virus engine detection," said the report.

In one example, every instruction had five or six extra jumps that added nothing to the functionality.

The malware is typically contained in an executable file inside a ZIP archive attached to the email. This is often disguised as a PDF file or a Microsoft Office document by relying on hidden file extensions. In Windows, if the "Hide extensions for known file types" is turned on, the file name "malware.pdf.exe" is displayed as "malware.pdf".

Symantec also reports that the number if websites harbouring malware and other potentially unwanted programs such as spyware and adware has increased 25.5 percent since June.

Contact Stilgherrian at stil@stilgherrian.com, or follow him on Twitter at @stilgherrian.

Tags: malicious email, malware, News, Paul Wood, polymorphic malware, security, symantec, Symantec Intelligence Report July 2011

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Security Awareness Tip
Software security company www.clearswift.com gives some advice this holiday season to make sure employees don’t end up on Santa’s naughty list!


At a fundamental business level, social media is a useful additional tool for communicating and collaborating with customers, colleagues and new business prospects. From an HR point of view, the social web is not only useful for recruitment but also as a knowledge network. At an employee level, social media is changing the way we work: Employees increasingly expect to be able to access personal technology and services in the workplace. As the lines between work and home life blur, staff are looking for greater flexibility in their roles; working from home is an increasing trend, but so too is ‘home-ing from work’, where staff expect to be able to perform personal tasks at work.

But social media brings risk and reward to business in equal measure. Information security is a key concern: Many organisations view social media channels as yet another route along which sensitive data can escape from the business, whether accidentally or maliciously. On top of this, senior management may be concerned about the amount of time employees spend on social networks.

This cultural shift raises new questions about trust in the workplace, the balance of power in employer / employee relationship and levels of control over people and content.


Organisations using content and web security technology can manage the way their staff use email and the internet without having to resort to a default position of mistrust. With a whopping third of ANZ employers completely blocking social media access at work, there’s a real danger of throwing the benefits of collaboration out with the risks.


It doesn’t have to be that way.

Trust breeds responsibility: People underestimate the amount of company time they spend on personal browsing. Allow staff to view their own web usage and foster more responsible behaviour without undermining trust.


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