[UPH-07-02] Firefly Media Server DoS

[UPH-07-02]
UnprotectedHex.com security advisory [07-02]
Discovered by nnp

Discovered : 1 August 2007
Reported to the vendor : 13 October 2007
Fixed by vendor : 21 October 2007

Vulnerability class : Remote DoS

Affected product : mt-dappd/Firefly Media Server
Version : <= 0.2.4
Product details:
www.fireflymediaserver.org/
'''
The purpose of this project is built the best server software to serve digital music to
the Roku Soundbridge and iTunes; to be able to serve the widest variety of digital music
content over the widest range of devices
'''

File/Function/line : webserver.c/ws_decodepassword/1399

Cause: Null pointer dereference. There is an unchecked increment of the 'header'
variable until a space character is encountered. If a space character is not encountered
the pointer is incremented/dereferenced until out of bounds memory is hit. Exploiting
this depends on the state of memory at the time so the exploit constantly sends a header
with no data as part of the authorization header until a crash occurs. This typically
occurs within seconds.

/* xlat table is initialized */
while(*header != ' ')
header++;

Proof of concept code : Yes