CVE-2017-15802 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.43 allows attackers to cause a denial of service or possibly have unspecified other impact via a crafted .dll file that is mishandled during an attempt to render the DLL icon, related to "Data from Faulting Address controls Branch Selection starting at ntdll_77310000!LdrpResCompareResourceNames+0x0000000000000087."
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Analysis
by VulDB Data Team • 11/29/2019
CVE-2017-15802 represents a critical vulnerability in XnView Classic for Windows version 2.43 that demonstrates a classic buffer overflow condition within the dynamic link library handling mechanism. This flaw occurs when the application attempts to process a specially crafted .dll file during icon rendering operations, specifically within the ntdll component of the windows operating system. The vulnerability manifests at the ntdll_77310000!LdrpResCompareResourceNames+0x0000000000000087 address, indicating a fault in the resource name comparison routine that governs how windows loads and processes dynamic libraries. The root cause stems from insufficient input validation and improper bounds checking when parsing maliciously constructed dll files, creating a condition where attacker-controlled data can manipulate the program flow and potentially execute arbitrary code.
The technical exploitation of this vulnerability leverages the Windows loader mechanism's handling of resource names in dynamic libraries, specifically targeting the LdrpResCompareResourceNames function which is responsible for comparing resource names during library loading. When a malicious .dll file is encountered, the application's icon extraction process fails to properly validate the resource data structure, leading to memory corruption that can result in denial of service conditions or more severe impacts including privilege escalation. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read errors that can lead to information disclosure and system compromise. The attack vector operates through social engineering techniques where users unknowingly open or preview maliciously crafted dll files, making this a particularly dangerous vulnerability in environments where users frequently handle untrusted file content.
The operational impact of CVE-2017-15802 extends beyond simple denial of service scenarios, as the vulnerability can potentially enable remote code execution depending on the execution context and system configuration. When exploited successfully, the vulnerability allows attackers to manipulate the program execution flow through controlled memory corruption, potentially leading to privilege escalation from user level to system level access. The vulnerability affects Windows systems where XnView Classic is installed and actively processes file icons, making it particularly dangerous in enterprise environments where users may encounter malicious files through email attachments, file sharing, or web browsing activities. Security researchers have identified this issue as part of the broader ATT&CK tactic of privilege escalation through exploitation of software vulnerabilities, specifically mapping to T1068 which involves exploiting vulnerabilities in legitimate programs.
Mitigation strategies for CVE-2017-15802 should focus on both immediate defensive measures and long-term remediation approaches. Organizations should immediately disable or remove XnView Classic from affected systems until a patch is available, as this vulnerability cannot be effectively mitigated through configuration changes alone. The most effective immediate solution involves updating to a patched version of XnView Classic that properly validates dll file structures during icon rendering operations. System administrators should also implement strict file type filtering and sandboxing mechanisms to prevent automatic execution of potentially malicious files, particularly focusing on dll files that might be encountered during file browsing operations. Network-level protections including email filtering and web proxy configurations can help reduce the attack surface by preventing users from downloading or accessing malicious files. Additionally, implementing application whitelisting policies and monitoring for unusual process execution patterns can help detect exploitation attempts, while regular security audits should verify that all systems have been properly updated and that no vulnerable versions remain in use.