LogMeIn LastPass up to 4.9.1 onloadwff.js HTML Document denial of service

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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A vulnerability was found in LogMeIn LastPass up to 4.9.1. It has been rated as problematic. This issue affects some unknown processing of the file onloadwff.js. The manipulation as part of a HTML Document leads to a denial of service vulnerability. Using CWE to declare the problem leads to CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. Impacted is availability. The summary by CVE is:

LogMeIn LastPass through 4.9.1 allows remote attackers to cause a denial of service (browser hang) via an HTML document because the resource consumption of onloadwff.js grows with the number of INPUT elements.

The bug was discovered 12/28/2017. The weakness was disclosed 04/18/2018 by Steve Birstok (haykuro) (Website). The advisory is shared at forums.lastpass.com. The identification of this vulnerability is CVE-2018-10193 since 04/17/2018. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details as well as a public exploit are known. MITRE ATT&CK project uses the attack technique T1499 for this issue.

A public exploit has been developed by Steve Birstok (haykuro) in HTML/Javascript and been published immediately after the advisory. The exploit is available at gist.githack.com. It is declared as proof-of-concept. The vulnerability was handled as a non-public zero-day exploit for at least 110 days. During that time the estimated underground price was around $0-$5k.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.





CPE 2.3info

CPE 2.2info


VulDB Meta Base Score: 5.9
VulDB Meta Temp Score: 5.8

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍



VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍


Class: Denial of service
CWE: CWE-404
ATT&CK: T1499

Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Proof-of-Concept
Author: Steve Birstok (haykuro)
Programming Language: 🔍
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍


Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍


Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍
Exploit Delay Time: 🔍


12/28/2017 🔍
04/17/2018 +109 days 🔍
04/17/2018 +0 days 🔍
04/18/2018 +1 days 🔍
04/18/2018 +0 days 🔍
04/18/2018 +0 days 🔍
02/01/2020 +654 days 🔍


Advisory: forums.lastpass.com
Researcher: Steve Birstok (haykuro)
Status: Not defined

CVE: CVE-2018-10193 (🔍)
scip Labs: https://www.scip.ch/en/?labs.20161013


Created: 04/18/2018 09:45 AM
Updated: 02/01/2020 01:38 PM
Changes: 04/18/2018 09:45 AM (54), 05/01/2018 11:59 AM (2), 05/01/2018 12:00 PM (5), 05/01/2018 12:01 PM (4), 02/01/2020 01:38 PM (1)
Complete: 🔍
Committer: haykuro


haykuro (+1)
6 years ago
A PoC is available here: https://gist.githack.com/anonymous/6aea35595465b8682e63b32a309995b5/raw/5dcf5ab8bcee753c07931c673b7f0912e480c21e/last_pass_demo.html

More info here: https://forums.lastpass.com/viewtopic.php?f=12&t=286955

Write up coming soon.

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