Exhibit 10.4

FIRST AMENDMENT TO

OPERATING AGREEMENT OF NEW LEAF  KBS JV, LLC

THIS FIRST AMENDMENT TO OPERATING AGREEMENT OF NEW  LEAF KBS JV, LLC, a Delaware limited liability company (this Amendment)
is dated and effective as of April 15, 2009 and entered into by and between NEW LEAF INDUSTRIAL PARTNERS FUND, L.P., a Delaware limited partnership (Managing Member) and KBS REIT ACQUISITION XXIII, LLC, a Delaware limited
liability company (Investor Member).

A.        Managing Member and
Investor Member entered into that certain Operating Agreement of New Leaf  KBS JV, LLC dated as of August 8, 2007 (the Agreement). Initially capitalized terms that are not otherwise defined in this Amendment shall
have the meaning assigned to such terms in the Agreement.

B.        Managing Member and
Investor Member desire to amend the Agreement in certain respects.

NOW, THEREFORE, in consideration of the mutual covenants set forth in
this Amendment and other good and valuable consideration, the parties agree as follows:

1.        Leasing Services Agreement Form.    Attached as Exhibit A to this Amendment is the Leasing Services Agreement, as currently approved by the Members.
Manager, on behalf of the Property Owner, may retain Leasing Agents for leasing services in accordance with, and subject to, the Leasing Services Agreement Form, with such modifications thereto which are commercially reasonable given the then
current market conditions with respect to the relevant Property.

2.        Reimbursement of
Expenses.    Notwithstanding anything to the contrary contained in Section 3.9 of the Agreement, and without limiting any expense reimbursements payable to Manager pursuant to Section 3.9 of the Agreement or
otherwise, the parties acknowledge and agree that Manager shall be entitled to reimbursement from the Company for the expenses set forth on Exhibit Bof this Amendment.

3.        Property Managers and Leasing Agents.    Exhibit C of the Agreement
is deleted and replaced with Exhibit C to this Amendment.

4.        Leasing
Services.    Exhibit G of the Agreement is deleted and replaced with Exhibit G to this Amendment.

5.        Miscellaneous.

(i)        Except
as provided in this Amendment, the Agreement is unchanged, shall remain in full force and effect and shall be binding upon the parties in accordance with its terms.

(ii)       Each provision of this Amendment shall be severable and if for any reason any provision or provisions herein are determined to be invalid, unenforceable or illegal under
any existing or future law, such invalidity, unenforceability or illegality shall not impair the operation of or affect those portions of this Amendment which are valid, enforceable and legal.



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(iii)     In the event of any conflict between the provisions of this Amendment
and the Agreement in existence prior to the effectiveness of this Amendment or any other document or instrument governing the affairs of the Company, the provisions of this Amendment shall prevail.

(iv)     This Amendment shall be governed by and construed under the laws of the State of Delaware (without regard to conflict
of laws principles), all rights and remedies being governed by said laws.

6.        Counterparts; Telefacsimile Execution.    This Amendment may be executed in multiple counterparts, each of which shall be an original but all of which
together shall constitute but one and the same agreement. Delivery of an executed counterpart of this Amendment by telefacsimile or electronic mail shall be equally as effective as delivery of an original of this Amendment. Any party delivering an
executed counterpart of this Amendment by telefacsimile or electronic mail also shall deliver an original counterpart of this Amendment, but the failure to deliver an original counterpart shall not affect the validity, enforceability and binding
effect of this Amendment. Signature pages may be detached from the counterparts and attached to a single copy of this Amendment to form one (1) document.

[Signatures on Following Page]



2



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IN WITNESS WHEREOF, Managing Member and Investor Member have executed this Amendment as of the date first
above-written.

MANAGING MEMBER:



|                                                                        |  |                                           
|----------------------------------------------------------------------- |  | ------------------------------------------
|NEW LEAF INDUSTRIAL PARTNERS FUND, L.P., a Delaware limited partnership
|                                                                        | 
|By:                                                                     |  | /s/ Jonathan Epstein                      
|                                                                        |  | Jonathan Epstein Authorized
Representative

INVESTOR MEMBER:

KBS REIT ACQUISITION XXIII, LLC,

a Delaware limited liability company



|By: | KBS REIT PROPERTIES, LLC,
|--- | -------------------------

a Delaware limited liability
company,

its sole member



| | By: | KBS LIMITED PARTNERSHIP,
| | --- | ------------------------

a Delaware limited partnership,

its sole member



| | By: | KBS REAL ESTATE INVESTMENT TRUST, INC.,
| | --- | ---------------------------------------

a Maryland
corporation,

general partner



| | By: | /s/ Charles J. Schreiber, Jr.
| | --- | -----------------------------

Charles J. Schreiber, Jr.

Chief Executive Officer



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EXHIBIT A

LEASING SERVICES AGREEMENT FORM

[To be attached]



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EXHIBIT B

REIMBURSEMENT OF EXPENSES

Marketing Expenses:

As consideration for the marketing services to be rendered by Manager to the Company (or on behalf of any Subtier Entity), the Company agrees to reimburse Manager for its marketing expenses in an amount equal to the
customary hourly rates typically charged by Manager with respect to similar marketing services, to the extent provided for in any Approved Annual Budget. Notwithstanding the foregoing, reimbursement of Manager for its marketing expenses shall be
conditioned upon Managers first providing Investor Member with a detailed invoice reasonably acceptable to Investor Member reflecting all marketing costs for which Manager is seeking reimbursement.

Accounting Expenses.

As consideration for the accounting services to
be rendered by Manager to the Company (or on behalf of any Subtier Entity), the Company agrees to reimburse Manager for its accounting expenses in an amount equal to the customary hourly rates typically charged by Manager with respect to similar
accounting services; provided, however, in no event will such reimbursement exceed One Hundred Eighty Thousand Dollars ($180,000) per Fiscal Year. Notwithstanding the foregoing, reimbursement of Manager for its accounting expenses shall be
conditioned upon Managers first providing Investor Member with a detailed invoice reasonably acceptable to Investor Member reflecting all accounting costs for which Manager is seeking reimbursement.



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EXHIBIT C

LIST OF PROPERTY MANAGERS AND LEASING AGENTS

Property Managers:

Hackman Capital Partners, LLC

PM Realty Group, L.P.

Calare Properties, Inc.

Notwithstanding the foregoing, any Property Manager
shall maintain, or cause to be maintained, books and records which comply with the Sarbanes Oxley.

Leasing Agents:

Cushman & Wakefield

Stubblebine

CBRE

Binswanger

Knewmark Knight Frank

Paul Johnson & Associates



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EXHIBIT G

SCHEDULE OF MAXIMUM LEASING COMMISSIONS



|                             |  |                           |  |               |  |       |  |                                                  |  |                             
|---------------------------- |  | ------------------------- |  | ------------- |  | ----- |  | ------------------------------------------------ |  | ----------------------------
|Property Name                |  | Street Address            |  | City          |  | State |  | Leasing Commissions New                          |  | Leasing CommissionsRenewal  
|15 Independence Dr.          |  | 15 Independence Dr.       |  | Devens        |  | MA    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|Home Depot Building          |  | 9410 Heinz Way            |  | Commerce City |  | CO    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|United Plastics              |  | 1040 Sheridan St.         |  | Chicopee      |  | MA    |  | 6% of the aggregate rent on co-broker/5% direct  |  | 2 1/2% of the aggregate rent
|Friendlies                   |  | 1045 Sheridan St.         |  | Chicopee      |  | MA    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|Woods Equipment Corp         |  | 151 Suffolk Ln.           |  | Gardner       |  | MA    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|1111 Southhampton Rd         |  | 1111 Southhampton Rd.     |  | Westfield     |  | MA    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|100 Adams Rd                 |  | 100 Adams Rd              |  | Clinton       |  | MA    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|111 Adams Rd                 |  | 111 Adams Rd              |  | Clinton       |  | MA    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|Nashua Corp  Viega Building |  | 59 Daniel Webster Highway |  | Merrimack     |  | NH    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|Home Depot                   |  | 170 Highland Park Dr.     |  | Bloomfield    |  | CT    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|50 Independence Dr.          |  | 50 Independence Dr.       |  | Devens        |  | MA    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|Tyco, Masonite               |  | 100 Simplex Dr.           |  | Westminster   |  | MA    |  | $1.00/s.f. for cores 1&3/$.25/s.f. for core 4    |  | 2 1/2% of the aggregate rent
|495-515 Woburn St            |  | 495-515 Woburn St         |  | Tewksbury     |  | MA    |  | $.75/sf on a co-broker and $.50/sf direct        |  | 2 1/2% of the aggregate rent
|9700 W Gulf Bank Rd          |  | 60 Maple                  |  | Houston       |  | TX    |  | 6% of the gross rent on co- broker/ 5% direct    |  | 2 1/2% of the aggregate rent
|1000 E I 20                  |  | 1000 E I 20               |  | Abilene       |  | TX    |  | 6% of the aggregate rent on co-broker/ 5% direct |  | 3% of the aggregate rent    



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|                       |  |                       |  |            |  |    |  |                                                    |  |                             
|---------------------- |  | --------------------- |  | ---------- |  | -- |  | -------------------------------------------------- |  | ----------------------------
|Home Depot             |  | 2200 Business Center  |  | Corsicana  |  | TX |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent
|133 Jackson Rd         |  | 133 Jackson Rd        |  | Ellicott   |  | NY |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent
|Penn Traffic Portfolio |  | 1200 State Fair Blvd. |  | Geddes     |  | NY |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent
|3407 Walters Rd        |  | 3407 Walters Rd       |  | Van Buren  |  | NY |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent
|851 Beaver Dr.         |  | 851 Beaver Dr.        |  | Du Bois    |  | PA |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent
|Shaffer Rd & Rt 255    |  | Shaffer Rd & Rt 255   |  | Du Bois    |  | PA |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent
|Dial Corp              |  | 480 Sprague St        |  | Dedham     |  | MA |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent
|85 Moosup Pond Rd      |  | 85 Moosup Pond Rd     |  | Plainfield |  | CT |  | 7.5% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|555 Taylor Rd          |  | 555 Taylor Rd         |  | Enfield    |  | CT |  | 7.5% of the aggregate rent on co-broker/ 5% direct |  | 2 1/2% of the aggregate rent
|625 University Ave     |  | 625 University Ave    |  | Norwood    |  | MA |  | 6% of the aggregate rent on co-broker/ 5% direct   |  | 2 1/2% of the aggregate rent

*In addition to the foregoing, Manager shall be entitled to receive a leasing commission (Managers
Fee) equal to (a) 1% of the aggregate rent for all new leases, and (b) 2.5% for renewal leases. In no event shall Managers Fee be subject to the Schedule of Maximum Leasing Commissions set forth above. Managers Fee shall
be payable according to the same payment schedule of any co-broker or direct broker agreement, or if there is no such broker, upon execution of any new lease or lease renewal, as applicable. During any transition period between property managers,
any fees payable to any prior property manager with respect to leasing activities shall be paid from amounts otherwise distributable to Manager pursuant to the previous sentence.