CVE-2017-10773 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.40 might allow attackers to cause a denial of service or possibly have unspecified other impact via a crafted .rle file, related to "Data from Faulting Address controls Branch Selection starting at MSCTF!_CtfImeCreateThreadMgr+0x00000000000000a8."
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Analysis
by VulDB Data Team • 10/22/2019
The vulnerability identified as CVE-2017-10773 affects XnView Classic for Windows version 2.40 and represents a critical security flaw that can lead to denial of service conditions or potentially more severe impacts through manipulation of specially crafted .rle files. This issue originates from the MSCTF!_CtfImeCreateThreadMgr component within the Windows operating system, specifically at offset 0x00000000000000a8, where data from a faulting address controls branch selection. The vulnerability demonstrates how improper handling of malformed image data can create exploitable conditions that extend beyond simple application crashes into potential system-wide impacts.
The technical flaw manifests when XnView Classic processes a maliciously constructed .rle file, which triggers an unpredictable execution flow within the MSCTF component. This component is part of the Microsoft Text Services Framework responsible for managing input methods and text services in Windows environments. The faulting address data influences branch selection logic, creating a condition where attacker-controlled data can alter program execution paths. This type of vulnerability falls under the CWE-122 category of "Heap-based Buffer Overflow" and aligns with ATT&CK techniques involving privilege escalation and system resource exhaustion. The specific offset mentioned in the vulnerability description indicates a precise location within the Windows kernel where the exploitation occurs, making it particularly dangerous as it operates at a low system level.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as the unspecified other impacts could include arbitrary code execution or complete system compromise. When an attacker successfully exploits this flaw, they can potentially gain control over the affected system through the manipulation of text services and input method frameworks. The vulnerability affects systems running Windows versions that include the MSCTF component, making it particularly concerning for enterprise environments where XnView Classic is commonly used for image processing and viewing tasks. The attack vector is straightforward, requiring only that a user open a specially crafted .rle file, making it highly exploitable in social engineering scenarios.
Mitigation strategies for this vulnerability should include immediate patching of XnView Classic to version 2.41 or later, which contains the necessary fixes for this issue. System administrators should implement strict file validation procedures and restrict the opening of untrusted image files, particularly those with .rle extensions. Network-level controls can be deployed to block .rle files from suspicious sources or to scan incoming files for known malicious patterns. Additionally, implementing application whitelisting policies that restrict execution of untrusted image viewers can provide defense-in-depth. The vulnerability highlights the importance of proper input validation and memory management in third-party applications, particularly those that interface with system-level components like the Text Services Framework. Organizations should also consider monitoring for unusual system behavior that might indicate exploitation attempts and maintain up-to-date security intelligence feeds to identify similar vulnerabilities in other software components.