It is trivial to crash clamd using a malformed uuencoded message, resulting in a denial of service for all programs (e.g. SMTP daemons) relying on clamd running. The message must only contain one uuencoded line with an illegal line lenght, i.e. starting with a small letter. libclamav calculates the line lenght of an uuencoded line by taking the ASCII value of the first character minus 64 and does an `assert' if the length is not in the allowed range, effectively terminating the calling program. Fix: Add the following in files/patch-libclamav::message.c: How-To-Repeat: Save the following file to ~/clamtest.mbox, removing the leading 'X': XFrom - X Xbegin 644 byebye Xbyebye Xend Then do: # clamscan --mbox -v ~/clamtest.mbox assertion "(len >= 0) && (len <= 63)" failed: file "message.c", line 887 Abort (core dumped) or # clamdscan -v ~/clamtest.mbox; ps ax | grep clam
Responsible Changed From-To: freebsd-ports-bugs->eik I'll take it.
Argh! Fixed patch: --- libclamav/message.c.orig Wed Nov 5 11:59:53 2003 +++ libclamav/message.c Mon Feb 9 15:17:13 2004 @@ -878,13 +878,16 @@ if(strcasecmp(line, "end") == 0) break; - assert(strlen(line) <= 62); + if(strlen(line) > 62) + break; + if((line[0] & 0x3F) == ' ') break; len = *line++ - ' '; - assert((len >= 0) && (len <= 63)); + if(len < 0 || len > 63) + break; ptr = decode(line, ptr, uudecode, (len & 3) == 0); break;
This has been fixed in the latest code (see CVS) for sometime. -- Nigel Horne. Arranger, Composer, Typesetter. NJH Music, Barnsley, UK. ICQ#20252325 njh@despammed.com http://www.bandsman.co.uk
Nigel Horne wrote: > This has been fixed in the latest code (see CVS) for sometime. ... but not in the relase version, which most production servers will run.
Hi, In the attachment is a patch that was retreived directly from clamav-devel sources. Regards, Rui Lopes
State Changed From-To: open->closed fixed.