<PAGE>
                                                                   EXHIBIT 31(2)


                            CERTIFICATION PURSUANT TO
             RULE 13a-14(a) OF THE SECURITIES EXCHANGE ACT OF 1934,
                             AS ADOPTED PURSUANT TO
                  SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, John S. Heneghan, certify that:

1. I have reviewed this quarterly report on Form 10-Q of CNA Surety Corporation;

2. Based on my knowledge, this quarterly report does not contain any untrue
   statement of a material fact or omit to state a material fact necessary to
   make the statements made, in light of the circumstances under which such
   statements were made, not misleading with respect to the period covered by
   this quarterly report;

3. Based on my knowledge, the financial statements, and other financial
   information included in this quarterly report, fairly present in all material
   respects the financial condition, results of operations and cash flows of the
   registrant as of, and for, the periods presented in this quarterly report;

4. The registrant's other certifying officer and I are responsible for
   establishing and maintaining disclosure controls and procedures (as defined
   in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure
   controls and procedures to be designed under our supervision, to ensure that
   material information relating to the registrant, including its consolidated
   subsidiaries, is made known to us by others within those entities,
   particularly during the period in which this quarterly report is being
   prepared;

b) evaluated the effectiveness of the registrant's disclosure controls and
   procedures and presented in this quarterly report our conclusions about the
   effectiveness of the disclosure controls and procedures, as of the end of the
   period covered by this quarterly report based on such evaluation; and

c) disclosed in this quarterly report any change in the registrant's internal
   control over financial reporting that occurred during the registrant's most
   recent fiscal quarter (the registrant's fourth quarter in the case of an
   annual report) that has materially affected, or is reasonably likely to
   material affect, the registrant's internal control over financial reporting;
   and

5. The registrant's other certifying officer and I have disclosed, based on our
   most recent evaluation of internal control over financial reporting, to the
   registrant's auditors and the audit committee of registrant's board of
   directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or
   operation of internal control over financial reporting which are reasonably
   likely to adversely affect the registrant's ability to record, process,
   summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other
   employees who have a significant role in the registrant's internal controls
   over financial reporting; and

Date: August 12, 2003


/s/ John S. Heneghan
John S. Heneghan
Senior Vice President and Chief Financial Officer