Apple has published a support document discussing the risks and dangers inherent in jailbreaking an iPhone, or "installing software that makes unauthorized modifications to the iPhone OS." The risks, according to Apple, include the following:
- Device and application instability
- Unreliable voice and data
- Disruption of services
- Shortened battery life
- Compromised security
- Inability to apply future software updates
We've discussed the issue of compromised security on jailbroken iPhones here in the past. Apple says that, "Security compromises have been introduced by these modifications that could allow hackers to steal personal information, damage the device, attack the wireless network, or introduce malware or viruses." In fact, the jailbreaking an iPhone depends on exploiting of a vulnerability in the iPhone's OS. It is true that jailbroken iPhones - or phones of any type - are inherently less secure than "normal" phones. Security updates made to the device's OS cannot be applied if the user wants to use a jailbroken phone, at least not until the jailbreaking process itself is updated following the issuing of patches. Jailbreaking requires third-party software that is modified after every update to the iPhone's OS, and there is a period between an update and the release of new jailbreaking software during which users are especially vulnerable.
Nevertheless, jailbreaking remains popular. This is one of the reasons why Intego added the ability to scan an iPhone or iPod touch to VirusBarrier X5. (See this article for more on scanning an iPhone or iPod touch with VirusBarrier X5.) If you jailbreak your iPhone, you should be extremely careful, and you should check it often for malware.