The secret world of computer backdoors is one in which spooks access supposedly secure equipment and services, hackers plunder data and take remote control of computers, and network administrators innocently go about their business carrying out remote maintenance.

We usually associate backdoors with hackers because it’s a common technique used to bypass security and secretly access computers. As damaging as this can be there is also a bit more to backdoors:
  • A legitimate network administrator may intentionally create or install a backdoor program for troubleshooting or system maintenance.
  • A backdoor also refers to a secret portal that intelligence agencies use to gain access to computers.

Administrator access

  • Within the context of network administration a backdoor refers to a legitimate point of access embedded in a system or software program for remote administration.
  • Generally this kind of backdoor is undocumented and is used for the maintenance and upkeep of software or a system.
  • Some administrative backdoors are protected with a hardcoded username and password that cannot be changed
  • Some backdoors are known only by the software maker. Not even the system owner is aware of them. These are typically written by the programmer who is developing the application or operating system so it can be accessed for troubleshooting or other purposes.

Hacker backdoors

  • Hackers often search for administrator backdoors and those known only to software vendors.
  • However, they can also install backdoors on a targeted system using malware like a remote access Trojan (RAT). A RAT is a malware program that includes a back door for administrative control over the target computer.
  • RATs are usually downloaded invisibly if for instance someone downloads a game or video from suspect online sources. They are also loaded into email attachments.
  • Once a RAT is installed hackers can use the backdoor to remotely access and control the system or steal data.

The spooks

Whether you love, loath or are absolutely indifferent to notorious whistleblower Edward Snowden, his undercover escapades certainly blew the lid on some of the tricks that intelligence services get up to.

The documents he leaked revealed just how down and dirty intelligence can be, all in the interest of national security of course.
  • For years the US National Security Agency (NSA), in partnership with Britain’s GCHQ, pressured companies into installing secret backdoors in their products. Many of them appear to have complied.
  • They had a strong focus on those companies that developed encryption systems. They weren’t happy that they couldn’t access these products.
  • Of course the reasoning is simple; they wanted to circumvent and undermine security protections to secretly access systems and data.

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Infamous backdoors

There are many backdoors that have been used to inflict damage.
  • MyDoom is often reported to be the most devastating computer virus ever, racking up $38 billion worth of damages.
  • This worm was initially installed via a backdoor and according to some sources was so ubiquitous it slowed internet access around the world by 10 percent, with some websites slowing by as much as 50 percent.

But when it comes to backdoors in products there have also been lots of instances with many companies typically saying they weren’t aware of the backdoor. Here are a few of the more notorious examples:
  • WhatsApp

In 2017 a security researcher discovered a backdoor in WhatsApp's end-to-end encryption. Apparently the backdoor could allow Facebook and others, such as government agencies to intercept and read WhatsApp's encrypted messages. 
  • Juniper Networks

At the tail end of 2015 network equipment provider Juniper admitted to suspicious researchers that its encryption random number generator contained a backdoor that would allow anyone with knowledge of it to eavesdrop on secure VPN connections. 
  • Huawei

The huge Chinese equipment maker was accused of building backdoors into its telecoms equipment. In 2012 a US Congressional investigation concluded that the firm should be banned from the US over state surveillance worries. In the UK BT had been installing Huawei equipment since 2007.It was bit late to do anything beyond GCHQ setting up a special unit to monitor Huawei systems in cooperation with BT.