Software Engineering Institute

NGSSoftware has released Insight Security Research Advisory #NISR06022002B that describes a number of vulnerabilities in the Apache PL/SQL module used by Oracle9i Application Server (iAS). This document addresses a buffer overflow vulnerability caused by a malformed HTTP Authorization request.

Oracle iAS uses the Apache HTTP Server to provide web services, including access to stored procedures via the Oracle PL/SQL module (modpplsql or mod_plsql). In iAS, PL/SQL is used to communicate with the database and generate HTML that can be interpreted by a web browser. The PL/SQL module handles authentication requests for various elements of Oracle iAS, such as stored procedures and Database Access Descriptors (DAD). If necessary, the PL/SQL module will prompt for credentials using the Authorization mechanism of the HTTP protocol. Section 14.8 of RFC 2616 describes HTTP Authorization and RFC 2617 describes the Basic and Digest HTTP Authentication schemes. A malformed HTTP Authorization request that contains a crafted password parameter could trigger a buffer overflow, executing arbitrary code with the privileges of the Apache service.

The vulnerable PL/SQL module may also be used by Oracle9i Database and Oracle8i Database.

An unauthenticated, remote attacker could cause a denial of service or execute arbitrary code on the system with the privileges of the Apache process. Since the Apache service typically runs with SYSTEM privileges on Windows NT and Windows 2000, an attacker may be able to gain complete control of the system.

Apply Patch
Apply the appropriate patch referenced in Oracle Security Alert #28.

Disable Vulnerable Service

Disable the vulnerable service (modplsql or mod_plsql in Apache).

Block or Restrict Access

Monitor and/or restrict access to the Apache service (typically 80/tcp). It may be possible to use TCP Wrapper or similar technology to provide improved access control and logging. Additionally, an application-level firewall may be able to filter requests made to Apache. Note that these workarounds are designed to limit access and detect exploit attempts. These workarounds do not prevent exploitation of this vulnerability.