HBGary has pulled out of the RSA Conference in the US claiming to have received threats from hacktivist group Anonymous.
The security firm has cancelled all talks at the show and removed its booth from the conference altogether.
"A group of aggressive hackers known as Anonymous illegally broke into computer systems and stole proprietary and confidential information from HBGary. This breach was in violation of federal and state laws, and stolen information was publicly released without our consent," a statement from HBGary read.
"In addition to the data theft, HBGary individuals have received numerous threats of violence including threats at our tradeshow booth."
The firm said it is working with law enforcement bodies "to bring those responsible to justice."
Earlier this week, it emerged Anonymous had leaked yet more emails it had gained access to after hacking into the security firm.
The spat between Anonymous and HBGary started when chief executive of the latter Aaron Barr told the Financial Times he had discovered the identities of senior members of the hacktivist group.
The group responded instantly, infiltrating HBGary's network and website, as well as Barr's Twitter account.
With this week's additional email leak, Anonymous said it was angered that Greg Hoglund, chief operating officer of HBGary, had reportedly been pushing legal action against the group.
HBGary had been working with law enforcement in the US to counter Anonymous' efforts.
A number of arrests have been made in relation to investigations into the hacker group.
