Effective 2019 Sep 15, Cisco will no longer publish non-Cisco product alerts. Cisco will continue to publish Security Advisories to address third-party software vulnerabilities per the Cisco Security Vulnerability Policy.
Multivendor Vulnerability Alert
PHP imap_open Function Arbitrary Command Execution Vulnerability
A vulnerability in the imap_open function of PHP could allow an authenticated, remote attacker to execute arbitrary commands on a targeted system.
The vulnerability exists because the imap_open function of the affected software improperly filters mailbox names before passing them to the rsh or ssh commands. If the rsh and ssh functionalities are enabled and the rsh command is a symbolic link to the ssh command, an attacker could exploit this vulnerability by sending a malicious IMAP server name containing a -oProxyCommand argument to the targeted system. A successful exploit could allow the attacker to bypass other disabled exec functions in the affected software, which the attacker could leverage to execute arbitrary shell commands on the targeted system.
Functional code that exploits this vulnerability is available as part of the Metasploit Framework.
PHP has confirmed the vulnerability and released a software patch.
To exploit this vulnerability, the attacker must have user-level access to the targeted system. This access requirement could reduce the likelihood of a successful exploit.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
Administrators are advised to monitor affected systems.
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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.