Cisco Addresses Critical Security Flaw in Secure Client Software
Cisco has recently issued patches to rectify a significant vulnerability in its Secure Client software, which poses a considerable risk of exploitation by malicious actors. This flaw allows intruders to initiate a VPN session impersonating a targeted user, potentially compromising sensitive data and network integrity.
Identified as CVE-2024-20337, the vulnerability holds a CVSS score of 8.2, indicative of its severity. Cisco’s advisory characterizes the flaw as enabling unauthenticated remote attackers to perform carriage return line feed (CRLF) injection attacks. This occurs due to inadequate validation of user inputs, allowing attackers to manipulate the VPN session process by tricking users into clicking on specially crafted links.
The immediate risk involves attackers executing arbitrary scripts in the browser environment or extracting critical information, such as valid SAML tokens, from the affected user’s session. Such access would permit the adversary to establish remote VPN connections with the full privileges of the compromised user account. However, additional authentication would still be necessary for access to underlying resources and services behind the VPN headend.
This vulnerability affects Cisco’s Secure Client software across Windows, Linux, and macOS platforms. The patch has been applied in versions 4.10.08025 and 5.1.2.42, specifically resolving exploits identified in earlier releases. Security professionals are urged to migrate to these fixed versions promptly to mitigate potential exposure.
The flaw was discovered by Amazon security researcher Paulos Yibelo Mesfin, who emphasized its capacity to grant attackers access to local internal networks when a targeted user visits compromised websites, posing considerable risks to organizational security.
In addition to the CRLF injection vulnerability, Cisco resolved another critical issue identified as CVE-2024-20338, which carries a CVSS score of 7.3. This flaw allows authenticated local attackers to escalate privileges on affected devices running Secure Client for Linux, thereby broadening the attack surface within organizational networks. Cisco detailed that this exploit could enable an attacker to execute arbitrary code with root privileges by leveraging malicious library files and requiring administrator intervention to activate the exploit.
Given the nature of these vulnerabilities, various tactics and techniques from the MITRE ATT&CK framework may have been employed during the attack. Initial access through unvalidated user inputs aligns with tactics for exploiting trust relationships, whereas privilege escalation techniques manifest in the exploitation of CVE-2024-20338.
Business owners and cybersecurity professionals alike should stay vigilant and ensure that their software remains up to date, adopting proactive measures to reinforce their network security posture against such evolving threats. The timely application of Cisco’s patches is vital in mitigating risks associated with these notable vulnerabilities.
