CVE-2008-1379 in X11
Summary
by MITRE
Integer overflow in the fbShmPutImage function in the MIT-SHM extension in the X server 1.4 in X.Org X11R7.3 allows context-dependent attackers to read arbitrary process memory via crafted values for a Pixmap width and height.
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Analysis
by VulDB Data Team • 08/11/2019
The vulnerability described in CVE-2008-1379 represents a critical integer overflow flaw within the MIT-SHM extension of the X server version 1.4 in X.Org X11R7.3. This issue resides in the fbShmPutImage function which handles shared memory pixmap operations, making it particularly dangerous as it operates within the core graphics subsystem of Unix-like operating systems. The vulnerability stems from inadequate input validation when processing pixmap width and height parameters, creating a scenario where maliciously crafted values can cause integer arithmetic to wrap around, leading to unexpected behavior in memory management operations.
The technical exploitation of this vulnerability occurs through context-dependent attacker control of pixmap dimensions that exceed the maximum representable integer values. When the fbShmPutImage function processes these oversized dimensions, the integer overflow corrupts memory layout assumptions, potentially allowing attackers to manipulate memory pointers and access arbitrary process memory locations. This flaw falls under CWE-190, which specifically addresses integer overflow conditions, and more broadly relates to CWE-129, representing insufficient validation of length fields. The vulnerability demonstrates how seemingly benign graphics operations can become attack vectors when proper input sanitization is absent, particularly in systems where shared memory extensions facilitate high-performance graphics operations.
The operational impact of this vulnerability extends beyond simple memory disclosure, as it provides attackers with the capability to read arbitrary process memory, potentially exposing sensitive data including authentication tokens, cryptographic keys, or application secrets. Attackers could leverage this information to escalate privileges, perform session hijacking, or extract confidential information from running processes. The context-dependent nature of the attack means that exploitation requires specific conditions such as access to the X server environment or the ability to establish shared memory segments, but once achieved, the memory read capabilities can be devastating. This vulnerability aligns with ATT&CK technique T1059.007, which covers command and scripting interpreter, as it enables attackers to access system information and potentially escalate their privileges through memory-based attacks.
Mitigation strategies for CVE-2008-1379 should focus on immediate patch application to update the X server to versions that address the integer overflow in the fbShmPutImage function. Organizations should also implement proper input validation mechanisms that constrain pixmap dimensions to reasonable bounds and monitor shared memory operations for anomalous behavior. Additionally, system administrators should consider disabling unnecessary X server extensions when they are not required for specific applications, reducing the attack surface. The vulnerability highlights the importance of rigorous input validation in graphics subsystems and demonstrates how mathematical overflow conditions in memory management functions can create serious security implications. Regular security assessments of X server configurations and proper access controls for X11 sessions should be implemented to prevent unauthorized exploitation of such vulnerabilities.