CVE-2011-1823

What is Android OS?

Android is Google's mobile operating system, powering the vast majority of the world's smartphones and tablets. The Android architecture separates application code (running as unprivileged users) from system processes running as root. Privilege escalation vulnerabilities that allow apps to break this boundary are especially dangerous because they can enable persistent malware, bypass factory resets, and install rootkits that survive normal removal attempts.

Overview

CVE-2011-1823 is a privilege escalation vulnerability in the Android volume manager daemon (vold) that allows a local application with minimal privileges to gain root access. The flaw stems from vold trusting messages received from a PF_NETLINK socket without proper validation — a low-privilege process can craft and send malicious netlink messages that trick vold into executing arbitrary commands as root.

This vulnerability is the root cause behind the widely-used GingerBreak rooting tool and the Lotoor (also known as Exploit.AndroidOS.Lotoor) malware family, both of which weaponized this flaw to silently root Android devices.

Affected Versions

Technical Details

The vold daemon manages storage volumes (SD cards, USB drives) and runs as root. It listens for kernel events via a PF_NETLINK/NETLINK_KOBJECT_UEVENT socket. The vulnerability (CWE-190, integer overflow related) was that vold processed netlink messages received from user space without verifying that the sender was the kernel — any low-privilege process could write crafted messages to the same socket.

By sending specially crafted netlink messages to vold, a malicious application could manipulate the daemon into mounting arbitrary filesystems or executing shell commands as root. The fix committed to AOSP (commit c51920c) added a check to verify that netlink messages originated from the kernel (PID 0) rather than from user-space processes.

Attack characteristics:

• Requires only a low-privilege Android app (no special permissions beyond basic execution)
• No user interaction required after app installation
• Reliable across all Android 2.2/2.3 devices prior to the patch
• Root access is persistent for the lifetime of the device session

Discovery

The vulnerability was discovered by the Android rooting community and publicly released as the GingerBreak exploit tool in approximately April 2011, prior to formal CVE assignment and before a fix was broadly available. This "zero-day public release" approach was common in the Android rooting community, where researchers valued device customization access over responsible disclosure.

Exploitation Context

CVE-2011-1823 was exploited in two distinct contexts:

Legitimate rooting: GingerBreak was widely used by Android power users to root their devices — gaining full system access for customization, installing custom ROMs, and removing bloatware. The tool was downloaded millions of times.

Malicious exploitation: The Lotoor malware family (tracked by Kaspersky as Exploit.AndroidOS.Lotoor) used this vulnerability to silently root Android devices after being installed from third-party app markets. Once root access was achieved, Lotoor installed persistent backdoors, harvested credentials, and enabled remote control of the device. Kaspersky reported Lotoor was one of the most widespread Android malware families of 2011–2012.

Remediation

Android 2.3.4 and later versions include the fix. For devices that cannot be updated (end-of-life Android versions):

1. Replace the device with a supported Android version
2. For enterprise environments, enforce minimum Android version requirements via Mobile Device Management (MDM)
3. Restrict sideloading of apps from unknown sources via MDM policy
4. Deploy a mobile threat defense solution to detect rooting attempts and Lotoor indicators
5. Devices suspected of compromise should be factory reset (though persistent root malware may survive) — consider the device untrusted and retire it