CVE-2017-5029 in iTunes
Summary
by MITRE
The xsltAddTextString function in transform.c in libxslt 1.1.29, as used in Blink in Google Chrome prior to 57.0.2987.98 for Mac, Windows, and Linux and 57.0.2987.108 for Android, lacked a check for integer overflow during a size calculation, which allowed a remote attacker to perform an out of bounds memory write via a crafted HTML page.
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Analysis
by VulDB Data Team • 11/24/2022
The vulnerability identified as CVE-2017-5029 represents a critical integer overflow flaw within the libxslt library version 1.1.29, specifically affecting the xsltAddTextString function in the transform.c file. This vulnerability manifests in the Blink rendering engine used by Google Chrome across multiple platforms including Mac, Windows, Linux, and Android. The flaw occurs during the calculation of memory allocation sizes when processing XSLT transformations, creating a scenario where an attacker can manipulate the size calculation to trigger an out of bounds memory write condition. The vulnerability is particularly dangerous because it allows remote code execution through crafted HTML pages that contain malicious XSLT transformations, making it a prime target for browser-based attacks that can compromise user systems without requiring any user interaction beyond visiting a malicious website.
The technical nature of this vulnerability aligns with CWE-190, which describes integer overflow conditions that can lead to memory corruption and arbitrary code execution. The flaw specifically occurs when the xsltAddTextString function performs size calculations for memory allocation without proper overflow checking mechanisms. When an attacker crafts an HTML page containing malicious XSLT code with carefully manipulated string lengths, the function calculates an oversized buffer size that exceeds the intended memory boundaries. This integer overflow results in a memory write operation that extends beyond the allocated buffer, potentially overwriting adjacent memory locations with attacker-controlled data. The vulnerability operates at the intersection of memory safety and integer arithmetic, where the lack of proper bounds checking during size calculations creates a path for memory corruption that can be exploited to execute arbitrary code.
From an operational perspective, this vulnerability presents a significant threat to web browser security as it enables remote attackers to perform arbitrary code execution on affected systems. The impact is amplified by the widespread use of Google Chrome across multiple platforms, making the attack surface extremely broad. Attackers can leverage this vulnerability through drive-by download scenarios where simply visiting a compromised website is sufficient to trigger the exploit. The vulnerability also relates to several ATT&CK techniques including T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation, as successful exploitation can lead to full system compromise. The fact that this vulnerability affects multiple operating systems and Chrome versions demonstrates the extensive reach of the flaw and the importance of timely patching across all affected platforms.
The exploitation of this vulnerability requires careful crafting of XSLT transformations that can trigger the specific integer overflow condition in the xsltAddTextString function. Security researchers have identified that the flaw occurs when processing text strings that, when combined with the existing buffer size calculation logic, produce values that exceed the maximum representable integer, leading to a wraparound that results in insufficient memory allocation. This creates a scenario where subsequent memory write operations can overwrite critical memory regions, potentially including return addresses or function pointers. The vulnerability's impact is further compounded by the fact that it operates within the core rendering engine, meaning that successful exploitation can lead to complete system compromise. Organizations should implement immediate patch management procedures to address this vulnerability across all affected Chrome installations, as the window for exploitation remains open until patches are deployed. The vulnerability also highlights the importance of proper integer overflow checking in security-critical code paths, particularly in libraries that handle user-provided data such as XSLT transformations in web browsers.