Just one day after nasty security flaws were disclosed in Yahoo's Music Jukebox, miscreants have begun to actively exploit them.

The buggy Yahoo media player is one of at least three pieces of web software reported in the last week to be smitten by ActiveX flaws that leaves users wide open to attack. Elazar Broad, the researcher who disclosed the vulnerability on Sunday, also recently revealed critical flaws in the programs used to upload photos onto MySpace and Facebook. Sites that use the Anon Proxy Server are at risk of being remotely controlled by attackers exploiting a third recently disclosed ActiveX vulnerability.

According to Symantec's DeepSight Threat Management System, exploit code targeting the Yahoo media player installs a backdoor on vulnerable machines. Yahoo currently has no patch for the multiple vulnerabilities.

Two ActiveX controls in the player are susceptible to buffer overflow attacks because they fail to scrutinize code for malicious input. Broad posted proof-of-concept code on the Milw0rm site, and within about 24 hours exploits targeting one of the two vulnerabilities were found by Symantec honeypots. Symantec researchers say it's likely exploits the other flaw will also make it into the wild soon.

Vulnerability tracking service Secunia rates the vulnerabilities "extremely critical," its highest classification.

Yahoo Music Jukebox is the default software for playing music sold by Yahoo. The insecurity comes as Yahoo has announced plans to abandon an unlimited service and transfer users to RealNetworks' Rhapsody service.

It's been a busy week for Broad. Last Thursday, he disclosed a buffer overflow vulnerability in Aurigma's Image Uploader Control Library that put MySpace users at risk. He was back on Sunday to update additional ActiveX uploader tools distributed by Aurigma that were also vulnerable.

Of course, the easiest way to insulate yourself from one of these bugs is to simply uninstall the software. There are plenty of other ways to upload pics or listen to digital tunes, so that isn't really asking for much, now is it?

Those who are really stubborn, and have a sufficient technical foundation, can set the kill bit for the vulnerable CLSIDs. The SANS Internet Storm Center provides instructions here. ®