CVE-2008-4166 in Avant Browser
Summary
by MITRE
Integer overflow in the JavaScript engine in Avant Browser 11.7 Build 9 and earlier allows remote attackers to cause a denial of service (application crash) by attempting to URL encode a string containing many instances of an invalid character.
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability described in CVE-2008-4166 represents a critical integer overflow condition within the JavaScript engine of Avant Browser version 11.7 Build 9 and earlier. This flaw exists in the handling of URL encoding operations when processing strings containing numerous invalid characters, creating a scenario where malicious input can trigger unexpected behavior in the browser's execution environment. The issue stems from inadequate input validation and boundary checking within the JavaScript engine's string processing routines, specifically when dealing with character encoding transformations that involve integer arithmetic operations.
The technical implementation of this vulnerability involves the JavaScript engine's failure to properly validate integer values during URL encoding processes. When a string containing many instances of invalid characters is processed, the engine attempts to perform arithmetic operations on integer values that exceed their maximum representable range. This overflow condition causes the application to behave unpredictably, ultimately leading to a crash or complete application termination. The vulnerability is classified as a classic integer overflow issue, which maps to CWE-190, Integer Overflow or Wraparound, and specifically represents a variant where the overflow occurs during string manipulation operations within a web browser context.
The operational impact of this vulnerability extends beyond simple denial of service, as it provides remote attackers with a reliable method to disrupt browser functionality and potentially interrupt user sessions. Attackers can craft malicious web pages containing specially constructed strings with excessive invalid characters, which when processed by the vulnerable browser will cause immediate application instability. This type of vulnerability aligns with ATT&CK technique T1499.004, Network Denial of Service, as it enables attackers to cause service disruption through carefully crafted inputs. The vulnerability affects the browser's core JavaScript execution environment, making it particularly dangerous as it can be exploited through standard web browsing activities without requiring additional privileges or specialized attack vectors.
Mitigation strategies for this vulnerability primarily involve updating to patched versions of Avant Browser where the integer overflow conditions have been properly addressed through enhanced input validation and boundary checking mechanisms. System administrators should implement immediate updates to prevent exploitation, as the vulnerability does not require user interaction beyond normal web browsing. Organizations should also consider implementing network-based protections such as web application firewalls that can detect and block malicious URL encoding patterns. Additionally, browser security configurations should be reviewed to ensure that automatic URL encoding and character set handling are properly constrained. The fix typically involves implementing proper integer overflow detection and handling within the JavaScript engine's string processing functions, ensuring that arithmetic operations are validated against maximum representable values before execution occurs.