CVE-2014-9862 in FreeBSD
Summary
by MITRE
Integer signedness error in bspatch.c in bspatch in bsdiff, as used in Apple OS X before 10.11.6 and other products, allows remote attackers to execute arbitrary code or cause a denial of service (heap-based buffer overflow) via a crafted patch file.
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Analysis
by VulDB Data Team • 03/10/2019
The vulnerability described in CVE-2014-9862 represents a critical integer signedness error within the bspatch.c component of the bsdiff library, which is extensively utilized in Apple's operating systems including versions prior to macOS 10.11.6. This flaw exists at the core of how patch files are processed and validated, creating a pathway for malicious actors to exploit the system through specially crafted patch data. The issue stems from improper handling of signed and unsigned integer comparisons during the patch application process, specifically within the buffer allocation and memory management routines. The vulnerability manifests as a heap-based buffer overflow that can be triggered when the system attempts to apply a maliciously constructed patch file, potentially allowing attackers to execute arbitrary code with the privileges of the affected application or cause a denial of service condition.
The technical exploitation of this vulnerability involves the manipulation of integer values within the patch processing logic where signed and unsigned integers are improperly compared or converted. When bspatch processes a malformed patch file, the signedness error causes incorrect calculations in buffer size determinations, leading to insufficient memory allocation for data structures that subsequently overflow when the actual patch data is written. This type of error falls under the CWE-190 category of "Integer Overflow or Wraparound" and specifically relates to CWE-191 which deals with "Integer Underflow (Wrap or Wraparound)" and CWE-194 which addresses "Unsigned Integer Truncation." The flaw creates a condition where an attacker can control the amount of memory allocated for buffer operations, enabling them to write beyond allocated boundaries and potentially overwrite adjacent memory regions.
From an operational perspective, this vulnerability presents significant risks to systems running affected versions of Apple OS X, as it allows for remote code execution without requiring user interaction or elevated privileges. The impact extends beyond simple denial of service to include full system compromise, as the heap overflow can be leveraged to inject and execute malicious code within the context of the patch application process. The vulnerability affects not only Apple's own products but also other software systems that utilize the bsdiff library for patch management, making it a widespread concern across various software ecosystems. Security analysts have categorized this vulnerability under the MITRE ATT&CK framework in the technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1203 for "Exploitation for Client Execution" due to its potential for remote code execution and the nature of the attack vector through patch file manipulation.
The mitigation strategies for CVE-2014-9862 primarily involve applying the official security patches released by Apple for macOS 10.11.6 and subsequent versions, which correct the integer signedness error in the bspatch.c implementation. Organizations should also implement strict validation of patch files from trusted sources and consider network segmentation to limit the attack surface where patch application occurs. Additionally, system administrators should monitor for any unauthorized patch file installations and maintain up-to-date security configurations to prevent exploitation attempts. The vulnerability demonstrates the critical importance of proper integer handling in security-sensitive code and the potential consequences of overlooking signedness considerations in memory management operations, particularly in systems where patch management plays a crucial role in maintaining system integrity and security.