CVE-2010-4555 in SquirrelMail
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in SquirrelMail 1.4.21 and earlier allow remote attackers to inject arbitrary web script or HTML via vectors involving (1) drop-down selection lists, (2) the > (greater than) character in the SquirrelSpell spellchecking plugin, and (3) errors associated with the Index Order (aka options_order) page.
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Analysis
by VulDB Data Team • 11/14/2021
The vulnerability identified as CVE-2010-4555 represents a critical cross-site scripting weakness affecting SquirrelMail versions 1.4.21 and earlier, demonstrating the persistent challenges organizations face in securing web-based email clients. This vulnerability classifies under CWE-79 as a failure to sanitize user input, specifically within the context of web application security where malicious scripts can be injected into web pages viewed by other users. The flaw manifests through three distinct attack vectors that exploit different components of the SquirrelMail application interface, creating multiple pathways for attackers to compromise user sessions and potentially escalate their access within the email environment.
The technical implementation of this vulnerability occurs through three primary methods that all fall under the category of improper input validation and output encoding. The first vector involves drop-down selection lists where user-supplied data is not properly sanitized before being rendered back to the browser, allowing attackers to inject malicious scripts through carefully crafted selections. The second vulnerability exploits the SquirrelSpell spellchecking plugin where the greater than character is not adequately escaped, enabling attackers to manipulate the spellchecker's output to inject executable code. The third vector targets the Index Order page, where errors associated with the options_order functionality are displayed without proper HTML encoding, creating opportunities for script injection attacks that can be triggered by manipulating the order parameters.
The operational impact of CVE-2010-4555 extends beyond simple data theft or session hijacking, as it creates potential for more sophisticated attacks within the email ecosystem. When successful, these XSS vulnerabilities can enable attackers to steal session cookies, redirect users to malicious sites, deface web interfaces, or even execute commands within the context of the victim's browser session. The attack surface is particularly concerning for organizations using SquirrelMail as their primary email solution, as these vulnerabilities can be exploited by attackers without requiring authentication to the email system itself. The attack patterns align with ATT&CK technique T1566.001 for credential access through social engineering and T1584.004 for establishing persistence through web shell deployment, making these vulnerabilities particularly dangerous in enterprise environments.
Organizations affected by this vulnerability should immediately implement comprehensive mitigation strategies that address all three attack vectors simultaneously. The most effective immediate solution involves upgrading to SquirrelMail version 1.4.22 or later, which contains patches specifically designed to sanitize all user inputs before rendering them in the browser context. Additionally, administrators should implement strict input validation routines that escape special characters including the greater than symbol, implement proper output encoding for all dynamic content, and establish Content Security Policy headers to limit script execution within the application. The remediation process should also include comprehensive security testing of all user-supplied inputs and regular vulnerability assessments to identify similar weaknesses in other web applications within the organization's infrastructure.