Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
The vulnerability is due to improper boundary checks by the HTTP inspection engine while inspecting transit HTTP traffic in the affected device. An unauthenticated, remote attacker could exploit this vulnerability by sending crafted HTTP packets through the targeted device. If successful, the attacker could cause the device to reload, resulting in a DoS condition.
Cisco has confirmed the vulnerability in a security advisory and released software updates.
Indicators of Compromise
Cisco has published a list of affected Cisco IOS Software releases in the security advisory. The Vendor Announcements section of this alert contains a link to the advisory.
The vulnerability is due to improper boundary checks by the HTTP inspection engine while inspecting transit HTTP traffic via TCP port 80 on the affected device. The processing of crafted HTTP messages can cause the affected device to reload or to trigger memory leaks that may result in system instabilities.
An unauthenticated, remote attacker could exploit this vulnerability by sending crafted HTTP packets through the targeted device. If successful, the attacker could cause the device to reload, resulting in a DoS condition.
To exploit the vulnerability, the attacker may provide a malicious link and use misleading language or instructions to persuade the user to follow the provided link. Following the provided link cause crafted HTTP packets to travel through the affected device, triggering the vulnerability.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only privileged users to access administration or management systems.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators are advised to monitor critical systems.
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at firstname.lastname@example.org.
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.