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Worm Wriggles Through Yahoo! Mail Flaw
Jasen Bell writes to mention a ZDNet article about a clever new worm affecting users of Yahoo!'s email service. The virus uses a flaw in JavaScript to infect a computer when an email is opened from the user's web-based mail. From the article: "The worm, which was spotted in the wild early this morning, has hit the remote server more than 100,000 times, forwarding Yahoo e-mail addresses harvested from unsuspecting users, Turner said. Although the worm is spreading quickly, and no patch has been issued, Symantec is rating the threat a '2.' The security vendor uses a 1-to-5 rating system, with '5' as its most severe category."
Yamanner arrives in a Yahoo mailbox bearing the subject header "New Graphic Site."
... I opened an email like this yesterday ... the reason being was because it was "from" one of my friends (they were marked as the sender). As soon as it opened I knew I f!cked up ... per a Javascript popup window shooting up ... grrr ...
Damn
Fixed: At the time of the advisory, there was no patch for the vulnerability. But by later on Monday, Yahoo said it had come up with a fix for the flaw, which it said had affected very few of its customers.
I have to say I agree with the low threat level. All the virus does is propogate and collect email addresses, and only on yahoo. If you have a yahoo email address, you're getting spam anyway, so how will you even know the difference?
Yesterday by The Register
My question is: who thought it was a good idea to enable JavaScript in emails? Someone at Yahoo! wasn't paying attention to basic security.
GetOuttaMySpace - The Anti-Social Network
The article only mentions the systems affected (only Windows systems apparently) but not the browsers. However, it is the browser that executes the Javascript code, which steals the e-mail addresses from the Yahoo! address book. So, are they sure that a Linux-based system with Mozilla (such as mine) would not be affected by the worm ?
In Soviet Russia, our new overlords are belong to all your base.
I thought the security of yahoo would have captured a old javascript virus by now. Bu i do not understand: how can this javascript break out the browsers? isn't yahoo just a webmail website? then how would the local pc be affected? why would you have to scan your pc as symantic tells you?
Ok, the virus can send a lot of e-mails and break the yahoo mail system. or si there something about yahoo mail i do not understand?
you could also not open werid emails from people you don't know
... and thus I received this worm email "from" one of my friends ... so it's not just coming from random accounts, it's coming from people who have you in their contact list.
Yeah, but this spreads via your Yahoo! contact list
Symantec is rating the threat a '2.'
The lowball number is interesting, especially given the fact that Symantec is the company charged with the task of keeping an outbreak like this from happening:
Symantec to scan Yahoo Mail for viruses
ZuluPad, the wiki notepad on crack
The article is lacking many details, like specifically which browsers seem to be vulnerable to this problem, or even if this is a browser bug that it is exploiting.... It could be a server side problem they are exploiting, or a client side browser bug. It says the vulnerable systems are every Windows OS, so it appears to be a client side problem with Internet Exploder, although from the article it is impossible to determine this.
Just copy-pasted this off symantec:
Category 5 - Very Severe
Highly dangerous threat type, very difficult to contain. All machines should download the latest virus definitions immediately and execute a scan. Email servers may need to come down. All three threat metrics must be High.
* Wild: High
* Damage: High
* Distribution: High
Category 4 - Severe
Dangerous threat type, difficult to contain. The latest virus definitions should be downloaded immediately and deployed.
* Wild: High
* Damage or Distribution: High
Category 3 - Moderate
Threat type characterized either as highly wild (but reasonably harmless and containable) or potentially dangerous (and uncontainable) if released into the wild.
* Wild: High
or
* Damage: High and Distribution: High
Category 2 - Low
Threat type characterized either as low or moderate wild threat (but reasonably harmless and containable) or non-wild threat characterized by an unusual damage or spread routine, or perhaps by some feature of the virus that makes headlines in the news.
* Damage: High
or
* Distribution: High
or
* Wild: Low or Moderate
Category 1 - Very Low
Poses little threat to users. Rarely even makes headlines. No reports in the wild.
* Wild: Low
* Damage or Distribution: Low
Ironically, those of us with no contacts in our yahoo mail make for the best of friends!
This issue is a bit more complicated than you think.
I just got a wave of mails in my gmail box that are from random senders, with multiple small 1-4k attachements.
Anyone have any idea if this works on/through gmail too?
-Styopa
I am the bastard of base minus 12! Turing was the ejaculate of my complete machine!
from Learn about threat levels.
ThreatCon Level 1
Low : Basic network posture This condition applies when there is no discernible network incident activity and no malicious code activity with a moderate or severe risk rating. Under these conditions, only a routine security posture, designed to defeat normal network threats, is warranted. Automated systems and alerting mechanisms should be used.
Threatcon Level 2
Medium : Increased alertness
This condition applies when knowledge or the expectation of attack activity is present, without specific events occurring or when malicious code reaches a moderate risk rating. Under this condition, a careful examination of vulnerable and exposed systems is appropriate, security applications should be updated with new signatures and/or rules as soon as they become available and careful monitoring of logs is recommended. Changes to the security infrastructure are not required.
Threatcon Level 3
High : Known threat
This condition applies when an isolated threat to the computing infrastructure is currently underway or when malicious code reaches a severe risk rating. Under this condition, increased monitoring is necessary, security applications should be updated with new signatures and/or rules as soon as they become available and redeployment and reconfiguration of security systems is recommended. People should be able to maintain this posture for a few weeks at a time, as threats come and go.
Threatcon Level 4
Extreme : Full alert
This condition applies when extreme global network incident activity is in progress. Implementation of measures in this Threat Condition for more than a short period probably will create hardship and affect the normal operations of network infrastructure.
The article doesn't really mention the behavior of the worm and is actually slightly misleading. It doesn't "infect" your computer per se, it harvests your address book contacts and then spams them. From a different article:
Once executed, the worm forwards itself to an infected users' contacts on Yahoo! Mail. It also harvests these address and sends them to a remote internet server. Only contacts with an email address of either @yahoo.com or @yahoogroups.com are hit by this behaviour.
Lameness filter got me. Here is a link.
--fatboy
In short, I believe there should be some very stiff penalties to pay if it is proven that someone has written and deployed malware of this sort. There should be prison time and forfeiture of any money and assets acquired as a result of gains from this activity.
People often complain that punishment is too severe for this otherwise 'harmless' activity (and often compared to more heinous crimes such as assault, robbery, murder sex/child related crimes) and that damages are quite often exaggerated beyond reason. I can't say much about exaggerated damages, but I can say that in addition to other classifications of crimes, I also consider the following:
Planned/premeditated or not. Many aspects of the more heinous crimes where punishment is often less than these "white collar" crimes are not planned or premeditated. They are driven by little more than emotional or other motives. There is something more cold, more dark and indeed more arrogant when it comes to crimes such as the act of creating and deploying an internet worm. There is no question that what they are doing is immoral and illegal. They perform the act believing they will not be caught, that they will profit from the act and seemingly that it is somehow their right to take advantages of weaknesses in security simply because they are 'superior' in some way.
I see a noticable decline in the amount of spam in my inboxes of late. People claimed that the current federal legislation regarding spam wasn't enough and yet I see stories of people being prosecuted under these law successfully and when these people are put out of business, most all see a difference -- an improvement. It's working.
We don't need more legislation, but we do need to up the level of aggression in persuing these people and up the amount of punishment they are given when they are caught. While they are thinking about their planned attacks, they need to have cause to consider the potential cost to their lives as well.
If you did not open a mail whose subject was "New Graphic Site", you are not infected.
c /data/js.yamanner@m.html
Reference: Symantec advisory at http://securityresponse.symantec.com/avcenter/ven
A flaw in whose JS implementation then?
# cat
Damn, my RAM is full of llamas.
we're at terror alert orange! Which means something might go down somewhere in some way at some point in time. So look sharp!
Some people tend to think that this worm is harmless (just "spreading itself"). But the worm actually sends the harvested email adresses to an external site - www.av3.net [which I wouldn't dare to browse to].
Here are the technical details of the worm:
1) Arrives on the compromised computer as an HTML email containing Javascript. The email may have the following characteristics:
From: Varies
Subject: New Graphic Site
Message body: Note: forwarded message attached.
2) Once the email is opened the worm exploits a vulnerability in the Yahoo email service to run a script.
3) Sends a copy of itself to certain email addresses gathered from the Yahoo email folders.
4) Targets email addresses from the @yahoo.com and @yahoogroups.com domains.
5) Contacts the following URL:
[http://]www.av3.net/index.htm
6) Sends a list of email addresses gathered to the above URL.
"flaw in JavaScript" - you really mean "flaw in JavaScript" or flaw in the implementation of the so-called "JavaScript"? I mean - all browsers with "JavaScript" are affected? Including mobile devices, linuxes, unixes...?
Well, I've got to get back to work. When I stop rowing, the slave ship just goes in circles.
Using cryptographic signatures to verify that an email is really from your friend, before you trust its contents, simply isn't an option.
well, the email *was* from his friend. His friend was infected. If his friend was using a standalone email client and using cryptographic signatures, then most likely, his friend would have entered his password for PGP or whatever, and that password would be stored in memory, and then when the virus took over his account and started sending mail, the virus would sign the mail.
So in this particular instance, I don't see how a standalone client would help things.
Don't see anything on the home page, my.yahoo, or even the login page of yahoo mail.
That's pretty shitty. How hard would it be to add a warning and some helpful directions to the template of the login page?
-William Shatner can be neither created nor destroyed.
I agree with the parent on the bullet points, but I think the conclusion "death to webmail" is barking up the wrong tree. The real issue goes back to point number two: rendered in too powerful an environment. If e-mail was ALWAYS treated as text, instead of trying to support HTML and mime types blah blah then having a safe webmail interface would simply mean a control that shows the text as text only with no possible execution. Simple and what e-mail was always meant to be. If you need to send "pretty" stuff then send it as an attachment and let that be what it is.
> The worm itself (at least from the description here) sounds relatively serious
Huh? All the descriptions I've seen say it just forwards itself to people in your Yahoo! contact list. I've seen nothing about it doing any damage to your PC, browser, or even your Yahoo! mail account. How is that worthy of a rating more than two? Unless I'm missing something, 2 sounds too high. Is there some other evil effect that was discovered and not posted in the messages I've seen so far?
I don't have a problem with rendering HTML in webmail or any other mail. Javascript is not HTML, however, and should NEVER be activated with webmail. A proper webmail client needs to filter out all script tags before display. They are not needed.
Do a search on Sourceforge for it. Let's you download all your Yahoo mail with any POP3 compatable client. There are others for hotmail and other services, but of course Yahoo POPS is the relevant one to this issue. As you can see, there is already an incentive to start using it instead - keeps away those nasty web-based worms. You can always still disable images/javascript in your e-mail client just the same as your browser. Think how many times do you need javascript on to read an e-mail versus make a website work? Problem solved.
Bless Firefox and the NoScript (https://addons.mozilla.org/firefox/722/) extension.
It's fixed on yahoo's servers now, but according to the source link posted earlier, the flaw that's being exploited seems to be a bug in how yahoo parses html attributes. The bug sends itself as:
/ ma_mail_1.gif'
<img src='http://us.i1.yimg.com/us.yimg.com/i/us/nt/ma
target=""onload="whole bunch of crappy javascript here that uses only
single quotes and just goes on and on">
Note the lack of a space between the 'target' bit and the 'onload' bit. Now, apparently "target" is one of the HTML attributes that yahoo allows through on an IMG tag (why?). Anyway, it appears that yahoo's servers see both the target and the onload bit as one big long target attribute and let it through, whereas most browsers see that as a separate "target" and "onload" attribute and execute the javascript as soon as the image (one of the standard yahoo mail images, so it'll likely already be in the browser cache) is loaded.
The lesson here? I'm not really sure, beyond "double- and triple-check your parsing routines, since they will be used in security-sensitive code".