CVE-2007-5989 in Skype
Summary
by MITRE
Unspecified vulnerability in the skype4com URI handler in Skype before 3.6 GOLD allows remote attackers to execute arbitrary code via "short string values" that result in heap corruption.
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Analysis
by VulDB Data Team • 06/02/2025
The vulnerability identified as CVE-2007-5989 represents a critical heap corruption issue within the skype4com URI handler component of Skype software versions prior to 3.6 GOLD. This flaw exists within the Skype application programming interface that facilitates communication between Skype and external applications through URI schemes. The vulnerability specifically manifests when processing "short string values" that are passed to the URI handler, creating conditions where memory corruption can occur in the heap memory region. The skype4com component serves as a bridge between Skype and other software applications, enabling features such as click-to-call functionality and integration with third-party applications through standardized URI protocols. When maliciously crafted short strings are processed through this handler, they can overwrite adjacent memory locations in the heap, potentially leading to arbitrary code execution.
The technical exploitation of this vulnerability involves the manipulation of input parameters within Skype's URI processing mechanism. The heap corruption occurs due to insufficient bounds checking and memory management within the skype4com handler when dealing with short string inputs. This type of vulnerability falls under the category of memory corruption vulnerabilities, specifically heap-based buffer overflows as classified by CWE-121. The flaw demonstrates characteristics of a classic heap overflow where the application fails to properly validate the length of input strings before processing them in memory allocation contexts. Attackers can craft malicious URI schemes containing specially formatted short strings that, when processed by the vulnerable skype4com handler, trigger the heap corruption conditions. The vulnerability is particularly dangerous because it allows remote code execution without requiring local system access, making it a significant security risk for users who might encounter malicious URIs in web content or email messages.
From an operational impact perspective, this vulnerability poses substantial risks to enterprise and individual users who rely on Skype for communication. The remote execution capability means that attackers can potentially compromise systems simply by having victims click on malicious links or visit compromised websites that contain crafted Skype URIs. The vulnerability affects Skype versions prior to 3.6 GOLD, indicating that it was present in a significant portion of the user base at the time of discovery. The heap corruption can lead to various malicious outcomes including system crashes, privilege escalation, or full system compromise depending on the execution environment and available privileges. The vulnerability also represents a significant concern for organizations that may have Skype integrated into their business communication workflows, as it could be exploited to gain unauthorized access to corporate networks through social engineering attacks.
Mitigation strategies for this vulnerability primarily focus on immediate software updates and system hardening measures. The most effective approach is upgrading to Skype version 3.6 GOLD or later, which contains the necessary patches to address the heap corruption issue in the skype4com URI handler. Organizations should implement strict URI validation policies and consider disabling or restricting the use of external URI handlers when possible. Network-level protections can include filtering malicious URI patterns and implementing web application firewalls to block suspicious requests targeting Skype components. The vulnerability demonstrates the importance of proper input validation and memory management practices in software development, aligning with ATT&CK technique T1203 for legitimate credential exposure and T1059 for command and scripting interpreter usage. Security teams should also consider implementing monitoring for unusual Skype URI processing activities and establish incident response procedures to handle potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of regular security updates and the potential risks associated with legacy software components that may contain undiscovered vulnerabilities.