tenacious_boron_b8f85ad4
liblzma.so.5.6.1 | 605861f833fc181c7cdcabd5577ddb8989bea332648a8f498b4eef89b8f85ad4
247.80 KB
ELF Executable

Natural Language Summary

Benign

Verdict: Benign

The observed behavior aligns with a high-quality compression library (liblzma) integrated into an application or as a library component. The only atypical behavior is a transient GOT patch used for CPU feature probing, which is isolated to the resolver initialization and restored immediately. The absence of network, persistence, or credential access supports a benign posture. The multithreaded design with bounds checks indicates robustness against resource exhaustion and memory errors.


Summary

The binary is a compression/stream-processing component closely aligned with liblzma/libxz functionality. It implements a multithreaded encoder/decoder pipeline with per-block worker threads, indexing, and header/footer management. The code demonstrates advanced performance optimizations (IFUNC CRC32/CRC64 with PCLMUL/SSSE3, and CPU feature probing with a transient GOT patch during resolver initialization). No evidence of network activity, persistence, privilege escalation, or credential access. The GOT patch appears to be a narrow, defensive probe rather than a malicious hook.

Orchestration

The binary implements a multithreaded streaming compression/encoding/decoding pipeline consistent with liblzma/libxz behavior. High-level orchestration is performed by large multistate functions that coordinate input blocks, memory budgeting, context allocation, worker thread creation, indexing, and finalization. Notable orchestrators include:

  • sub_426820: a large multistate engine that orchestrates reading blocks, computing memory requirements, allocating contexts, creating worker threads, performing indexing and finalization (calls to lzma_index_hash_append, lzma_stream_footer_encode, etc.).
  • sub_428160 / sub_428460: writer/encoder state machine and worker-pool scheduler; handle state transitions for header, block encoding, index append and footer.
  • sub_42b660 and sub_42b1e0: worker threads that process per-block encoding tasks; they wait on condition variables, call application callbacks for data, and move completed blocks to the parent queue.

The runtime flow shows explicit state-machine and staged execution with shared context structures guarded by mutexes and condition variables. Per-block counters, queue depths, and error codes are tracked by the parent context.

Installation

No direct installation artifacts (registry/plist/systemd/cron) or explicit persistence mechanisms observed. The binary appears to be a compression library or component rather than an installer or dropper. Configuration and runtime behavior are driven by embedded or callback-driven interfaces.

Persistence

No evidence of persistence mechanisms or privilege escalation vectors. The code operates in user-space as a library/component, not a service or daemon.

Code Protection

Code appears unobfuscated with clear function names and symbols. The only unusual behavior is the IFUNC resolver's transient GOT patch during CPU feature probing, described below. No string encryption, control-flow flattening, or opaque predicates were observed.

Environment Awareness

The binary uses CPU feature probing to select optimized implementations (CRC32/CRC64) via IFUNC resolvers. A transient GOT patch is used during load-time CPUID probing to robustly determine available features. The patch is limited to an internal GOT slot pointing to a local CPUID wrapper and is restored immediately after the probe; no external or persistent changes are observed.

Runtime Behaviors

Typical runtime path for encoding:

  1. Initialize top-level encoder/stream context via sub_428f10/sub_4291e0/sub_427cd0 (allocate internal structures, init mutexes/condvars, build stream header).
  2. Inputs are accepted via application callbacks; payloads are validated and sliced (see sub_42b500 bounds checks).
  3. Worker threads (sub_42b660/sub_42b1e0) fetch data in chunks up to a cap of 0x4000 bytes, encode blocks via lzma_block_* helpers, and return completed blocks to the parent queue.
  4. The orchestrator updates index/hash structures (lzma_index_* APIs), writes headers/footers, and dispatches encoded output via callbacks (e.g., sub_425ad0).
  5. Graceful stop/join semantics are provided by helpers like sub_429b70, sub_429c50, sub_429d50.

Network Communication

No network access observed in the analyzed code paths. The library operates entirely on in-process data streams with user-supplied input/output callbacks.

Data Handling

Data is supplied and consumed via application callbacks; input buffers are validated; output is produced via the write callback. The bounds checks include a maximum block size and size-field sanity checks (e.g., 0x4000 chunk cap, 0x10000 size limit). There is no evidence of external data exfiltration.

Cryptography

No cryptographic algorithms (AES, RSA, etc.) appear in the analyzed paths. CRC32/CRC64 checksums are implemented via vectorized paths using PCLMUL/SSSE3 hardware acceleration for stream integrity rather than confidentiality.

Credential Access

No credential-retrieval APIs or credential harvesting routines observed (LSASS, keychains, PAM, /etc/shadow, etc.).

Destructive Actions

No destructive operations detected (no secure delete, MBR tampering, backup disabling, etc.).

Build Quality

High build quality with explicit resource management, thread synchronization, and bounds checks. The presence of IFUNC resolvers and CPU feature gating indicates performance-oriented optimization. No evident error-path neglect or resource leaks in the analyzed code paths.

Platform Specific Notes

Architecture: x86/x86_64 with SSE/SSSE3/PCLMUL optimized paths for CRC computations. Threading via pthreads with CLOCK_MONOTONIC preferred via pthread_condattr_setclock when available. IFUNC resolvers rely on writable GOT for resolver dispatch; transient GOT patching is constrained to an internal symbol and restored after probing.

Indicators

Type

Library symbol

Value

liblzma

Referenced By

global import table, many functions (e.g., lzma_block_header_size, lzma_index_init)

Indication

Core library participation for LZMA/XZ stream compression/encoding.

Type

Function symbol

Value

lzma_crc32

Referenced By

IFUNC resolver at 0x406bf0

Indication

Hardware-dispatched CRC32 implementation; CPU feature probing and selection.

Type

Function symbol

Value

lzma_crc64

Referenced By

IFUNC resolver at 0x406ff0

Indication

Hardware-dispatched CRC64 implementation; optimized vector path (PCLMUL/SSSE3).

Type

Constant / IP

Value

0x43bfd8

Referenced By

sub_404784 (transient GOT patch) and IFUNC resolver analysis

Indication

GOT transient patch targets internal CPUID-wrapper slot; demonstrates self-patching during resolver initialization.

Type

Constant / Function

Value

sub_4046f0

Referenced By

sub_404784 (GOT target), IFUNC cpuid helper

Indication

Local CPUID helper used to query CPU features.

Type

Function

Value

sub_421f50

Referenced By

sub_404784 (transient hook) and IFUNC analysis

Indication

Robust CPU probing prior to IFUNC resolution; possible signal-based probing or platform compatibility checks.

Type

String (Symbol Names)

Value

lzma_block_header_size, lzma_block_header_encode, lzma_block_uncomp_encode, lzma_filters_free, lzma_index_*

Referenced By

sub_42b660 and sub_426820

Indication

Evidence of embedded liblzma code and stream/index orchestration.

Type

Constant

Value

0x4000

Referenced By

sub_42b1e0, sub_42b660

Indication

Chunk cap used by per-block worker callbacks.

Type

Constant

Value

0x10000

Referenced By

sub_42b500

Indication

Buffer scanning bounds and parsed size limits.

Type

Function (pthreads)

Value

pthread_create, pthread_cond_wait, pthread_mutex_lock

Referenced By

Many functions

Indication

Multithreaded architecture with worker pools and synchronization primitives.

Delphos Labs may make errors. Manual verification is recommended.