The hackers posted a mocking, obscenity-laced screed against President Barack Obama after he delivered his State of the Union address on Thursday.
Speaker Nancy Pelosi and House Republican Leader John Boehner have sent a letter to chief administrative officer Daniel Beard, requesting 'an immediate and comprehensive assessment of how hackers were able to deface the websites of nearly 50 House Members and Committees'.
The incident indicate that further review of security procedures are needed, the two leaders said, adding that from initial reports, these intrusions appear to be related to one website vendor which has had previous security failures.
"While many members have expressed satisfaction with the vendor in question, this is the second time in a year websites hosted and supported by this vendor have been compromised," they said.
"We, therefore, request that your office work with the Committee on House Administration to review the security standards for House vendors and to assess whether this vendor, and others, have adhered to those standards," the letter said.
"We also request that you take immediate action to protect against breaches of the House firewalls and to ensure website security of all House offices," they said.