SUMMARY

Certain encryption applications permit compression directly in the message body of an encrypted email file. Symantec Encryption Desktop will attempt decompression and decryption of these specifically formatted incoming email files without properly limiting maximum file size during the decompression process. Decryption of an excessively large compressed message could cause high memory and CPU usage resulting in a denial-of-service (DoS) as the system becomes unresponsive during the decompression attempt.

AFFECTED PRODUCTS

ISSUES

MITIGATION

Details

Symantec was notified that Symantec Encryption Desktop is susceptible to creating a DoS condition on a client system when decrypting a specifically formatted/compressed incoming encrypted email message. Symantec Encryption Desktop fails to properly limit decompressed file size during the decryption process. Certain encryption applications allow compression directly in the encrypted mail file which is decrypted and decompressed by Symantec Encrypted Desktop on receipt by the mail client.  A malicious individual can encrypt a specifically formatted and encrypted email message and send it to a targeted user.  Depending on the option setting for the mail client, Symantec Encryption Desktop will attempt the decryption process upon receipt of the malformed email without user intervention.  By not properly restricting size limitations during the decompression portion of the decryption, this could result in excessive CPU and memory usage. Successful exploitation of this issue could cause a system to become unresponsive and potentially crash.    

Symantec Response

Symantec engineers verified this issue and have released an update in Symantec Encryption Desktop 10.3.2 MP3.

Update information

Customers may obtain Symantec Desktop Encryption maintenance updates through their normal Symantec support locations.

Best Practices

As part of normal best practices, Symantec strongly recommends:

• Restrict access to administration or management systems to privileged users.
• Disable remote access if not required or restrict it to trusted/authorized systems only.
• Where possible, limit exposure of application and web interfaces to trusted/internal networks only.
• Keep all operating systems and applications updated with the latest vendor patches.
• Follow a multi-layered approach to security. Run both firewall and anti-malware applications, at a minimum, to provide multiple points of detection and protection to both inbound and outbound threats.
• Deploy network and host-based intrusion detection systems to monitor network traffic for signs of anomalous or suspicious activity. This may aid in detection of attacks or malicious activity related to exploitation of latent vulnerabilities

ACKNOWLEDGEMENTS

Symantec would like to thank Alexander Klink, n.runs professionals GmbH, for reporting the issue and working with Symantec as it was addressed.

REFERENCES

BID: Security Focus, http://www.securityfocus.com, has assigned a Bugtraq ID (BID) to this issue for inclusion in the Security Focus vulnerability database.

CVE: This issue is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems.