FreeBSD VuXML: Documenting security issues in FreeBSD and the FreeBSD Ports Collection

gnupg -- RSA Key Extraction via Low-Bandwidth Acoustic Cryptanalysis attack

Affected packages
gnupg < 1.4.16
gnupg1 < 1.4.16


VuXML ID 2e5715f8-67f7-11e3-9811-b499baab0cbe
Discovery 2013-12-18
Entry 2013-12-18
Modified 2014-04-30

Werner Koch reports:

CVE-2013-4576 has been assigned to this security bug.

The paper describes two attacks. The first attack allows to distinguish keys: An attacker is able to notice which key is currently used for decryption. This is in general not a problem but may be used to reveal the information that a message, encrypted to a commonly not used key, has been received by the targeted machine. We do not have a software solution to mitigate this attack.

The second attack is more serious. It is an adaptive chosen ciphertext attack to reveal the private key. A possible scenario is that the attacker places a sensor (for example a standard smartphone) in the vicinity of the targeted machine. That machine is assumed to do unattended RSA decryption of received mails, for example by using a mail client which speeds up browsing by opportunistically decrypting mails expected to be read soon. While listening to the acoustic emanations of the targeted machine, the smartphone will send new encrypted messages to that machine and re-construct the private key bit by bit. A 4096 bit RSA key used on a laptop can be revealed within an hour.


CVE Name CVE-2013-4576