Overview
This blog post will delve into the details of a serious vulnerability found in File::Find::Rule through 0.34 for Perl, designated as CVE-2011-10007. This vulnerability could allow an attacker to execute arbitrary code when the `grep()` function encounters a specifically crafted filename – a significant issue because Perl is widely used for system management tasks, network programming, and web development. The vulnerability could potentially impact a vast number of servers and systems, putting sensitive data at risk and providing an entry point for further attacks.
Vulnerability Summary
CVE ID: CVE-2011-10007
Severity: High (8.8)
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: Arbitrary Code Execution, potential system compromise and data leakage
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Product | Affected Versions
File::Find::Rule for Perl | 0.34 and prior versions
How the Exploit Works
The vulnerability comes into play when the `grep()` function in File::Find::Rule encounters a filename that has been crafted in a specific way by an attacker. A file handle is opened with the two-argument form of `open()`. This allows the attacker-controlled filename to provide the MODE parameter to `open()`, which in turn transforms the filename into a command to be executed. With this, an attacker could potentially execute arbitrary code on the affected system.
Conceptual Example Code
The following is a conceptual example of how the vulnerability might be exploited:
$ mkdir /tmp/poc; echo > "/tmp/poc/|id"
$ perl -MFile::Find::Rule \
-E 'File::Find::Rule->grep("foo")->in("/tmp/poc")'In the above example, the directory `/tmp/poc` is created, and a file named `|id` is created within it. When the `grep()` function in File::Find::Rule traverses this directory, it encounters the maliciously crafted filename `|id`, which in turn opens a file handle with `open()` and executes the `id` command. The result is displayed, revealing the user and group IDs of the current user, demonstrating a successful arbitrary command execution.
Prevention and Mitigation
The best course of action to prevent exploitation of this vulnerability is to apply the vendor-provided patch. If for some reason this is not possible, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can help detect and prevent attempted exploits. However, these are only temporary solutions and do not address the root cause of the vulnerability. Therefore, updating to a patched version of File::Find::Rule is highly recommended.