CVE-2011-2074 in Skype
Summary
by MITRE
Unspecified vulnerability in the client in Skype 5.x before 5.1.0.922 on Mac OS X allows remote authenticated users to execute arbitrary code or cause a denial of service (application crash) via a crafted message.
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Analysis
by VulDB Data Team • 03/19/2021
The vulnerability identified as CVE-2011-2074 represents a critical security flaw within Skype's client implementation on macOS platforms. This issue affects Skype versions 5.x prior to 5.1.0.922, where the client application fails to properly validate incoming messages from authenticated remote users. The vulnerability stems from inadequate input sanitization mechanisms that allow malicious actors to craft specially formatted messages designed to exploit memory handling inconsistencies within the application's message processing pipeline. The flaw manifests when the client encounters malformed or specially crafted data structures that trigger unexpected behavior in the underlying code execution environment.
The technical nature of this vulnerability aligns with common software security weaknesses categorized under CWE-129, which deals with insufficient validation of length of input buffers. The flaw operates at the application layer where user-supplied data is processed without adequate boundary checks or sanitization routines. When authenticated remote users send crafted messages containing malicious payloads, the Skype client's message parser fails to properly handle these inputs, leading to memory corruption or stack overflow conditions. This type of vulnerability is particularly dangerous because it requires only authentication to exploit, meaning that legitimate users within the Skype network could potentially compromise other users' systems. The attack vector involves sending maliciously constructed messages through Skype's messaging infrastructure, which then gets processed by the vulnerable client application.
The operational impact of CVE-2011-2074 extends beyond simple denial of service conditions, as the vulnerability enables remote code execution capabilities that could allow attackers to gain complete control over affected systems. This represents a significant compromise of user security and privacy, as authenticated attackers can leverage this flaw to execute arbitrary code on target machines. The application crash conditions that occur during exploitation can be used as a vector for more sophisticated attacks, potentially leading to privilege escalation or persistent backdoor installation. The vulnerability affects the confidentiality, integrity, and availability of the Skype communication platform, as legitimate users cannot trust messages from authenticated sources. Additionally, the nature of this flaw means that any user with access to the Skype network could potentially exploit it, creating a broad attack surface that impacts all users of vulnerable versions.
Mitigation strategies for CVE-2011-2074 primarily focus on immediate software updates and system hardening measures. Users should upgrade to Skype version 5.1.0.922 or later, which includes patched message validation routines and improved input sanitization mechanisms. Organizations should implement network monitoring to detect unusual messaging patterns that could indicate exploitation attempts, while also maintaining strict access controls for Skype accounts to prevent unauthorized access. The vulnerability demonstrates the importance of proper input validation and buffer management in client applications, aligning with ATT&CK technique T1059.007 for command and scripting interpreter. Security professionals should also consider implementing network segmentation to limit the potential impact of such vulnerabilities, ensuring that even if one system is compromised, the attack cannot easily propagate to other network segments. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other communication applications that may be similarly affected by inadequate input validation mechanisms.