Clam Antivirus DoS vulnerability
Gentoo Linux Security Advisory
||GLSA 200402-07 / clamav
||February 17, 2004
||February 17, 2004: 01
All supported architectures
Oliver Eikemeier has reported a vulnerability in Clam AV, which can be
exploited by a malformed uuencoded message causing a denial of service for
programs that rely on the clamav daemon, such as SMTP daemons.
Clam AntiVirus is a GPLed anti-virus toolkit, designed for integration with
mail servers to perform attachment scanning. Clam AV also provides a
command line scanner and a tool for fetching updates of the virus database.
Oliver Eikemeier of Fillmore Labs discovered the overflow in Clam AV 0.65
when it handled malformed UUEncoded messages, causing the daemon to shut
The problem originated in libclamav which calculates the line length of an
uuencoded message by taking the ASCII value of the first character minus 64
while doing an assertion if the length is not in the allowed range,
effectively terminating the calling program as clamav would not be
A malformed message would cause a denial of service,
and depending on the server configuration this may impact other daemons
relying on Clam AV in a fatal manner.
There is no immediate workaround, a software upgrade is required.
All users are urged to upgrade their Clam AV installations to Clam AV 0.67:
Code Listing 3.1: Resolution
# emerge sync
# emerge -pv ">=app-antivirus/clamav-0.6.7"
# emerge ">=app-antivirus/clamav-0.6.7"