CVE-2015-3409 in Module::Signature
Summary
by MITRE
Untrusted search path vulnerability in Module::Signature before 0.75 allows local users to gain privileges via a Trojan horse module under the current working directory, as demonstrated by a Trojan horse Text::Diff module.
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Analysis
by VulDB Data Team • 05/18/2022
The vulnerability identified as CVE-2015-3409 represents a critical untrusted search path issue within the Module::Signature Perl module version 0.74 and earlier. This flaw resides in the module's handling of Perl module dependencies and loading mechanisms, creating a privilege escalation vector that can be exploited by local attackers. The vulnerability specifically affects systems where Perl modules are loaded from the current working directory without proper sanitization of the module search path. When Module::Signature attempts to verify or load dependent modules during signature validation, it does not properly isolate the module loading environment, allowing malicious actors to place specially crafted modules in the current working directory that will be loaded instead of the legitimate system modules.
This vulnerability operates under the principle of Trojan horse attacks where an attacker places a malicious module with the same name as a legitimate dependency in the current working directory from which the vulnerable application executes. The attack vector demonstrates the specific case involving Text::Diff module, where an attacker could create a malicious Text::Diff module in the working directory, causing the vulnerable Module::Signature to load the attacker-controlled code instead of the legitimate system module. The flaw stems from inadequate module path validation and the assumption that modules loaded from the current directory are trustworthy, which violates fundamental security principles of least privilege and secure module loading.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential code execution and system compromise. When a local user can manipulate the module loading process, they gain the ability to inject malicious code that executes with the privileges of the process running Module::Signature. This can lead to unauthorized access to system resources, data exfiltration, and further lateral movement within the compromised environment. The vulnerability is particularly concerning because it can be exploited without requiring elevated privileges initially, and the attack can be executed through normal user operations that involve module loading. The issue affects systems where Perl applications rely on Module::Signature for verifying module signatures, making it a potential vector for supply chain attacks against Perl-based systems.
Mitigation strategies for CVE-2015-3409 focus on both immediate patching and architectural improvements to module loading security. The primary remediation involves upgrading to Module::Signature version 0.75 or later, which includes proper sanitization of the module search path and implementation of secure module loading practices. Organizations should also implement proper module path isolation by ensuring that module loading occurs from predefined, trusted directories and that current working directory contents do not influence module resolution. Additional controls include implementing privilege separation for module verification processes, using sandboxed environments for module loading operations, and conducting regular security audits of Perl module installations. This vulnerability aligns with CWE-427 Uncontrolled Search Path Element and CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component, and maps to ATT&CK techniques including T1059 Command and Scripting Interpreter and T1548.001 Abuse of Functionality for privilege escalation through module manipulation.