Source: cve@mitre.org
Computer Associates InoculateIT Agent for Exchange Server does not recognize an e-mail virus attachment if the SMTP header is missing the "From" field, which allows remote attackers to bypass virus protection.
Computer Associates InoculateIT Agent for Exchange Server is vulnerable to a critical bypass, allowing attackers to deliver malicious attachments by omitting the 'From' header in SMTP emails. This flaw circumvents the agent's virus scanning, potentially leading to malware infection and system compromise. Successful exploitation grants attackers the ability to execute arbitrary code on the Exchange server.
Step 1: Craft Malicious Email: An attacker crafts an email containing a malicious attachment (e.g., a trojan, a virus, or a document with embedded macros). The email's SMTP header is modified to omit the 'From' field. Step 2: Email Delivery: The attacker sends the crafted email to a target Exchange Server protected by the vulnerable InoculateIT Agent. Step 3: Agent Processing: The InoculateIT Agent receives the email. Due to the missing 'From' header, the agent's virus scanning logic is bypassed. Step 4: Attachment Delivery: The email, including the malicious attachment, is delivered to the recipient's mailbox. Step 5: Malware Execution: If the recipient opens the malicious attachment, the malware executes, potentially leading to system compromise, data theft, or further attacks.
The vulnerability stems from a flawed implementation in the InoculateIT Agent's parsing logic. The agent fails to properly handle emails lacking the 'From' header, a valid but uncommon SMTP configuration. The agent's virus scanning routines are triggered based on the presence of the 'From' header. When the header is missing, the agent skips the scanning process, allowing malicious attachments to bypass security checks. This is a logic flaw, not a buffer overflow or memory corruption issue. The root cause is a missing check or a conditional statement that does not account for the absence of the 'From' header, leading to an unhandled state and a security bypass. The agent likely relies on the 'From' header to identify the sender and initiate the scanning process. The absence of this header causes the agent to skip the scanning step, allowing malicious attachments to pass through undetected.
Due to the age of the vulnerability, specific APT groups are unlikely to be actively targeting it. However, the simplicity of the bypass makes it attractive for opportunistic attackers and could be incorporated into broader campaigns. The vulnerability's impact on Exchange servers makes it a potential target for ransomware or data exfiltration attacks. Not listed on CISA KEV.
Network traffic analysis: Examine SMTP traffic for emails lacking the 'From' header. This can be done using tools like Wireshark or tcpdump.
Email server logs: Review Exchange server logs for emails that bypassed virus scanning. Look for entries indicating that the InoculateIT Agent did not scan certain emails.
Attachment analysis: Analyze attachments received by users for malicious content, especially if they originated from emails without a 'From' header.
SIEM alerts: Configure a SIEM to generate alerts based on the absence of the 'From' header in incoming emails and correlate these with attachment activity.
Upgrade or replace the vulnerable InoculateIT Agent with a patched version that correctly handles emails without the 'From' header and scans attachments regardless.
Implement a robust email gateway or security solution that performs comprehensive virus scanning, including attachments, and validates SMTP headers.
Configure Exchange server to reject or quarantine emails that lack the 'From' header. This is a temporary workaround, but it can mitigate the immediate risk.
Regularly update all security software, including antivirus and email security solutions.
Implement a defense-in-depth strategy, including endpoint detection and response (EDR) solutions to detect and respond to potential malware infections.