CVE-2008-7074 in i.Scribe
Summary
by MITRE
Format string vulnerability in MemeCode Software i.Scribe 1.88 through 2.00 before Beta9 allows remote SMTP servers to cause a denial of service (crash) and possibly execute arbitrary code via format string specifiers in a server response, which is not properly handled "when displaying the signon message."
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Analysis
by VulDB Data Team • 11/11/2024
The vulnerability described in CVE-2008-7074 represents a critical format string vulnerability within MemeCode Software i.Scribe email client version 1.88 through 2.00 before Beta9. This flaw exists in the application's handling of SMTP server responses during the signon process, where the software fails to properly sanitize format string specifiers that may be present in server replies. The vulnerability falls under the Common Weakness Enumeration category CWE-134, which specifically addresses the use of format strings without proper validation or sanitization. When an attacker controls an SMTP server and crafts malicious responses containing format string specifiers such as %s, %d, or %x, the vulnerable i.Scribe client becomes susceptible to exploitation.
The technical execution of this vulnerability occurs during the initial connection phase when the email client displays server signon messages. The application's improper handling of these messages creates a direct path for attackers to manipulate memory layout through carefully crafted format specifiers. This flaw enables attackers to either cause a denial of service through application crashes or potentially achieve arbitrary code execution on the victim's system. The vulnerability is particularly dangerous because it can be exploited remotely without requiring authentication or special privileges from the end user, making it a significant threat vector in email client security. The exploitability of this vulnerability is enhanced by the fact that email clients typically process server responses automatically without user intervention, creating an automated attack surface.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable full system compromise. When an attacker successfully exploits this format string vulnerability, they can manipulate the application's memory through stack-based buffer overflows, potentially leading to code execution with the privileges of the running process. The denial of service aspect alone can render email communication unusable for affected users, while the arbitrary code execution capability allows for more sophisticated attacks including privilege escalation, data exfiltration, or installation of persistent backdoors. This vulnerability directly relates to ATT&CK technique T1203, which covers exploitation of remote services through format string vulnerabilities, and T1059, covering command and scripting interpreters used for execution.
Mitigation strategies for this vulnerability require immediate patching of the affected i.Scribe versions to address the improper format string handling in signon message processing. Organizations should implement network-level controls to restrict SMTP server communications where possible, though this approach is limited given the nature of email protocols. The most effective remediation involves updating to patched versions of i.Scribe that properly validate and sanitize all server responses before displaying them to users. Security monitoring should include detection of unusual SMTP server responses that may contain format specifiers, and network segmentation can help limit the potential impact of successful exploitation. Additionally, administrators should consider implementing email filtering solutions that can detect and block suspicious server responses that may contain malicious format string sequences, providing defense-in-depth protection against this specific vulnerability class.