Britain's small businesses are taking risks with the security of their computer networks, say experts.
Poor security puts key data at risk
A survey has found that although most are protecting themselves against viruses, far fewer use software to stop other increasingly popular attacks.
Without extra protection small firms could find that malicious hackers can penetrate their networks to delete or steal data or use them to carry out attacks on others.
The survey also found that small firms are taking too long to apply the latest updates to software leaving loopholes open for others to exploit.
A survey carried out for security company Symantec has found that 97% of British small firms are using anti-virus software to protect themselves.
The firms questioned were confident that this meant that they were adequately protected with 96% saying they felt sure key data was secure.
Modern blended threats are designed to contain characteristics of many different types of cyber threat so they can probe security defences until they find a way in
But Symantec said that other findings of the survey showed that this confidence could be misplaced.
The survey found that 30% of firms had no firewall and 63% did nothing to monitor their networks to see if malicious hackers had compromised them.
"Modern blended threats, such as Nimda and Code Red, are designed to contain characteristics of many different types of cyber threat so they can probe security defences until they find a way in," said Kevin Chapman, spokesman for Symantec, "anti-virus alone will not stop them."
High-speed persistent net connections are a favourite target of computer criminals who regularly send out software probes to seek out networks that are not doing enough to protect themselves.
Many of the probes search for key weaknesses and holes in software that remain unpatched.
The survey found that small firms struggle to keep up with the number of patches that software makers issue to close loopholes.
Only 26% of the small businesses questioned install patches as soon as they became available and many said applying these patches was not a priority for them.
"No-one wants to be wise after the fact," said Mr Chapman.