Insecure Handling of URL Schemes in iOS
Nitesh Dhanjani posted a nice blog post as part of the SANS Application Security blog [1]. He discusses a particular interesting vulnerability in iOS. In iOS, like in other operating systems, application may register themselves to handle particular URL schemes. For example, a URL starting with "tel:" links to the telephone application.
However, how these URL schemes are dealt with depends on the application receiving these requests from the browser. The telephone application will for example prompt the user asking if it should dial the number. Skype on the other hand does not prompt the user. In order to prompt the user, the application has to fully load and start up. So at the very least the attacker may be able to load the application.
Desktop browsers, like for example Firefox, will first prompt the user for these external URL schemes (try "telnet:", which will launches a terminal and open telnet in most cases).
[1] https://blogs.sans.org/appsecstreetfighter/
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Johannes B. Ullrich, Ph.D.
SANS Technology Institute
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November 2010 Microsoft Black Tuesday Summary
Overview of the November 2010 Microsoft Patches and their status.
| # | Affected | Contra Indications | Known Exploits | Microsoft rating | ISC rating(*) | |
|---|---|---|---|---|---|---|
| clients | servers | |||||
| MS10-087 | Vulnerabiliites in Microsoft Office code execution (Replaces MS10-003 MS10-036) | |||||
| Microsoft Office CVE-2010-3333 CVE-2010-3334 CVE-2010-3335 CVE-2010-3336 CVE-2010-3337 |
KB 2423930 | exploit available. | Severity:Critical Exploitability: 1 |
Critical | Important | |
| MS10-088 | Vulnerabilities in Microsoft PowerPoint code execution (Replaces MS10-004, MS10-036, MS09-017) | |||||
| Microsoft Office CVE-2010-2572 CVE-2010-2573 |
KB 2293386 | . | Severity:Important Exploitability: 1 |
Critical | Important | |
| MS10-089 | Vulnerabilities in Forefront Unified Access Gateway escalation of privilege | |||||
| Forefront UAG CVE-2010-2732 CVE-2010-2733 CVE-2010-2734 CVE-2010-3936 |
KB 2316074 | . | Severity:Important Exploitability: 1 |
N/A | Important | |
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- We use 4 levels:
- PATCH NOW: Typically used where we see immediate danger of exploitation. Typical environments will want to deploy these patches ASAP. Workarounds are typically not accepted by users or are not possible. This rating is often used when typical deployments make it vulnerable and exploits are being used or easy to obtain or make.
- Critical: Anything that needs little to become "interesting" for the dark side. Best approach is to test and deploy ASAP. Workarounds can give more time to test.
- Important: Things where more testing and other measures can help.
- Less Urgent: Typically we expect the impact if left unpatched to be not that big a deal in the short term. Do not forget them however.
- The difference between the client and server rating is based on how you use the affected machine. We take into account the typical client and server deployment in the usage of the machine and the common measures people typically have in place already. Measures we presume are simple best practices for servers such as not using outlook, MSIE, word etc. to do traditional office or leisure work.
- The rating is not a risk analysis as such. It is a rating of importance of the vulnerability and the perceived or even predicted threat for affected systems. The rating does not account for the number of affected systems there are. It is for an affected system in a typical worst-case role.
- Only the organization itself is in a position to do a full risk analysis involving the presence (or lack of) affected systems, the actually implemented measures, the impact on their operation and the value of the assets involved.
- All patches released by a vendor are important enough to have a close look if you use the affected systems. There is little incentive for vendors to publicize patches that do not have some form of risk to them
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