Detect VDSO Hijacking in Elastic Security
Adversaries may inject malicious code into processes via VDSO hijacking in order to evade process-based defenses as well as possibly elevate privileges. Virtual dynamic shared object (vdso) hijacking is a method of executing arbitrary code in the address space of a separate live process. VDSO hijacking involves redirecting calls to dynamically linked shared libraries. Memory protections may prevent writing executable code to a process via Ptrace System Calls. However, an adversary may hijack the syscall interface code stubs mapped into a process from the vdso shared object to execute syscalls to open and map a malicious shared object. This code can then be invoked by redirecting the execution flow of the process via patched memory address references stored in a process' global offset table (which store absolute addresses of mapped library functions).
MITRE ATT&CK
- Technique
- T1055 Process Injection
- Sub-technique
- T1055.014 VDSO Hijacking
- Canonical reference
- https://attack.mitre.org/techniques/T1055/014/
Elastic Detection Query
sequence by host.id, process.pid with maxspan=30s
[process where event.type == "start" and
process.name != null and
process.name not in ("gdb", "strace", "ltrace", "valgrind", "java", "node", "dockerd", "containerd") and
host.os.type == "linux"]
[process where event.action == "exec" and
process.args : ("ptrace", "mprotect", "mmap") and
host.os.type == "linux"]
OR
any where host.os.type == "linux" and
event.dataset == "auditd" and
auditd.data.syscall in ("ptrace", "mprotect", "mmap") and
(
(auditd.data.syscall == "ptrace" and auditd.data.a0 in ("1", "2", "4", "5")) or
(auditd.data.syscall in ("mprotect", "mmap") and auditd.data.a2 : ("5", "7", "0x5", "0x7"))
) and
not process.executable : ("/usr/bin/gdb", "/usr/bin/strace", "/usr/bin/ltrace", "/usr/bin/valgrind", "/usr/bin/java", "*/dockerd", "*/containerd")Detects VDSO hijacking indicators on Linux endpoints by monitoring auditd events for suspicious ptrace PEEK/POKE operations and mprotect/mmap calls with executable flags that may indicate an adversary is patching the virtual dynamic shared object memory region or global offset table to redirect execution flow.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate debuggers (gdb, lldb) performing process inspection will trigger ptrace PEEK/POKE events during normal debugging sessions
- JIT compilation runtimes such as Java HotSpot, Node.js V8, and .NET CLR use mprotect with PROT_EXEC to make JIT-compiled memory regions executable
- Dynamic linker (ld-linux) and libc use mmap and mprotect with executable flags when loading shared libraries during application startup
Other platforms for T1055.014
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Inspect VDSO Memory Region
Expected signal: auditd: open() on /proc/<pid>/maps. The VDSO mapping shows the address range of the vdso in the target process.
- Test 2Check GOT Entries of Running Process
Expected signal: auditd: readlink and open on /proc/<pid>/exe, execution of readelf. No direct security events from GOT inspection — this is a defensive analysis technique.
- Test 3mprotect Executable Permission Change Detection
Expected signal: Syslog: python3 process execution. No actual mprotect call with PROT_EXEC in this safe test. In a real attack: auditd SYSCALL record with syscall=10 (mprotect) and a2 containing PROT_EXEC flag.
References (5)
- https://attack.mitre.org/techniques/T1055/014/
- https://web.archive.org/web/20210205211142/https://backtrace.io/blog/backtrace/elf-shared-library-injection-forensics/
- https://web.archive.org/web/20150711051625/http://vxer.org/lib/vrn00.html
- https://lwn.net/Articles/604515/
- https://web.archive.org/web/20051013084246/http://www.trilithium.com/johan/2005/08/linux-gate/
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