SAP Patches Critical Code Injection Flaw in TREX

SAP this week released its April 2017 set of patches. The most important of the 15 security notes resolves a Very High priority (Hot News) vulnerability in TREX / BWA that could allow an attacker to execute commands on the affected system.

Carrying a CVSS score of 9.4, and discovered by ERPScan, the note is the third in a series of patches that SAP has been releasing for NetWeaver Search and Classification (TREX) and NetWeaver Business Warehouse Accelerator (BWA) since December 2015, to prevent remote command execution. The issue was initially addressed with SAP Note 2234226, which was later updated with SAP Note 2273881, and now patched with SAP Note 2419592.

Onapsis, the firm that discovered the original vulnerability in 2015, explains that TREXNet, the internal communication protocol developed for TREX service, does not enforce any kind of authentication, but is required by TREX servers. This means that it exposes systems to malicious actors, who can remotely execute critical system and OS commands.

According to ERPScan, a company that specializes in securing SAP and Oracle products, because TREX is deployed in over a dozen SAP products, including SAP HANA, this vulnerability is considered one of the most widespread and severe SAP server-side issues. What’s more, the advisory with all the details was available on the web for 2 years, thus exposing numerous applications to attacks, ERPScan says.

“I reversed a protocol for HANA and then for the TREX search engine. As they share a common protocol, the exploit has been easily adapted. SAP fixed some features, but not everything affecting the core protocol. It was still possible to get full control on the server even with a patched TREX,” Mathieu Geli, Head of SAP Threat Intelligence at ERPScan and the researcher who discovered the issue, explains.

SAP’s April 2017 advisory reveals that three of the 15 security notes included in this month’s Security Patch Day were updates to previous notes, including one to a Remote Code Execution vulnerability in SAP GUI for Windows. Four of the security notes had a High severity rating, 8 were rated Medium risk, and two were considered Low severity.

ERPScan, on the other hand, says that there were 12 additional security notes included in this set of patches, for a total of 27 notes (17 SAP Security Patch Day Notes and 10 Support Package Notes).

7 of the patches were Missing Authorization Checks, 4 were Cross-Site request forgery, 3 Cross-Site Scripting, 2 Remote Code Execution (RCE), 2 XML external entity, 2 information disclosure, 2 denial of service, 1 open redirect, 1 buffer overflow, 1 directory traversal, and 2 other flaws.

In addition to the RCE flaw in TREX / BWA, SAP addressed three more vulnerabilities found by ERPScan researchers: a Cross-Site Scripting vulnerability in SAP NetWeaver Central Technical Configuration (CVSS Base Score: 6.3), a Cross-Site Scripting vulnerability in SAP NetWeaver Java Archiving Framework (CVSS Base Score: 6.1), and an XML external entity vulnerability in SAP Knowledge Management ICE Service (CVSS Base Score: 4.9).

Other critical issues SAP resolved this month include a Denial of service vulnerability in SAP SAPLPD (CVSS Base Score: 7.5), an XML external entity vulnerability in SAP Web Dynpro Flash Island (CVSS Base Score: 7.5), and a Missing authorization check vulnerability in SAP NetWeaver ADBC Demo Programs (CVSS Base Score: 6.3).

“After a pretty significant March Update, which included the highest critical note of the year (SAP HANA Self Service Vulnerability with CVSS 9.8 and other relevant High Priority notes) this is the second month with remote code injection vulnerabilities present. As a result, SAP Security Note #2419592 should be prioritized among the others as it implies a similar attack as the two others previously mentioned that impact TREX,” Onapsis says.

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