Whether it comes from hackers, disgruntled customers, or is simply a backlash against something you post, negative social media content can destroy trust in your brand in a matter of minutes.
"Social media is the most immediate threat to your company's reputation," says Pete Knott, digital consultant at reputation management consultancy Lansons.
"If not taken seriously it can and will directly impact your company financially and culturally."
Fake news remains one of the biggest challenges - despite machine learning crackdowns by networks such as Facebook and Twitter.
In May, for example, shares in the UK's Metro Bank plunged 11% before it could shake off inaccurate social media rumours that it was facing financial difficulties.
And according to Ilia Kolochenko of Geneva-based internet security company Immuniweb, the consequences could potentially be much worse.
'Dropping a bomb'
"Hackers can cause huge damage if they can find a way to post fake news on social media," he says.
"Imagine if they managed to hack into the BBC accounts and post a story about Iran dropping a nuclear bomb.
"The effects could be devastating - especially if other news networks picked up the story."
Social media posts don't have to be inaccurate to damage your brand, though. Sometimes, the truth hurts too.
In 2016, battery manufacturer Samsung SDI's market value plummeted by more than half a billion dollars when Tesla boss Elon Musk tweeted that the company was working with Panasonic on its next electric car.
If not properly thought out, your own posts can also cause problems, as US bank Chase found out earlier this year when it was accused of "poor shaming". It published a post suggesting customers with low bank balances save money by avoiding taking cabs and buying coffees.
Stealing your good name
Other threats include fraudsters taking your brand name in vain.
"Creative crooks often exploit big companies' names to run social media scams," Mr Kolochenko says.
"For example, they might set up an 'Amazon India Support' account on Twitter and ask customers who contact them about missing parcels to pay a customs fee."
And even posts by unknown customers can do a lot of damage if other users pick them up.
"Consumers have recognised that social media is a very fast way to get a response from customer services," says Claire Twohill, social media director at global PR agency FleishmanHillard.
"That's why social media attacks are often a direct result of a problem with the supply chain, or a change to a popular product.
"But whatever the reason, you need to react fast."
'Planning is crucial'
Masha Maksimava, a vice president at Belorussian social monitoring company Awario, says: "The key to online reputation management is handling negative feedback quickly to prevent it turning into crisis."
So it pays to be properly prepared.
"Planning is crucial," says Lopa Ghosh, an associate partner at global professional services provider EY.
Equally important, however, is not to overreact.
"You don't need to jump on every negative tweet," Ms Twohill says.
"Sometimes it's better to do nothing to avoid creating a crisis for no reason."
Either way, finding the right tone is key.
Get it spot on, and you might even be able to turn events to your favour.
"Social networks are a great place to rebuild reputation," Mr Knott says.
"So try to think about how you can use your response to a crisis to demonstrate your company's values and show its human side."
Employee activity is one of the biggest social media pitfalls.
Cyber criminals, for example, often use information gleaned from employees' social accounts to infiltrate an organisation.
Richard Horne, a cyber security partner at accountants PwC, says: "People expose a lot about themselves on social media.
"So attackers could look at someone's profile, see they love skiing and email them a malware link to a cheap chalet deal in Switzerland.
"It's a very common way of infecting companies' systems."
Passwords and posts
The challenge, therefore, is to manage how your employees use social media, without impinging on their rights.
"You can't monitor your employees' social media accounts - that's getting into very ethically murky waters," says Ms Ghosh.
"Instead, you have to educate them about passwords and what sort of thing they post."
It's also important to be clear about how they should respond - if at all - if the company becomes embroiled in a crisis.
Emma Harvey, founder of London-based reputation management specialist Seven Consultancy, says: "If an incident occurs, ensure that employees understand the protocol, and are not fanning the flames themselves by trying to defend the company online."
Take advantage of social monitoring tech
Monitoring, or listening, tools that use Application Programming Interfaces (APIs) provided by social networks to collect and analyse data can help you to build reputation and manage crises on social media.
"Setting up a social listening tool can be challenging, especially if your brand name is a common word such as Apple," Ms Maksimava says.
"So the main three things to look for are sentiment analysis, so you can handle negative mentions first; real-time results, so you can step in immediately; and flexibility, so you can exclude irrelevant mentions even if your keywords are ambiguous."
Just be careful to avoid invading people's privacy.
"There are definite benefits to using social listening tools, but it must be done in the right way," Mr Knott says.